The US and Arab partner nations today launched airstrikes on the Islamic State in Iraq and Syria (ISIS) targets in Syria.
The move is a significant escalation of America's military campaign against ISIS - who hold swathes of territory across the region.
Around 20 targets have been hit, including ISIS training and logistics sites.
The strikes have increased pressure on US President Barack Obama to commit US ground troops to fighting ISIS.
In Britain, Labour's Chuka Ummuna has warned that it is 'inconceivable' that Prime Minister David Cameron will commit Britain to joining in with the airstrikes without the approval of Parliament.
Meanwhile, Israeli forces say they have shot down a Syrian fighter jet which strayed into their air space.
The UN is preparing for 400,000 Kurdish refugees in Syria to flee into Turkey as ISIS continues to advance.
It has been revealed that the Syrian's were warned of the US-led strikes on ISIS in a letter from American Secretary of State John Kerry - which was received hours before the raids began.
To recap on the all the news and reaction as it happened, scroll down.
The United States and partner nations have carried out the first air strikes against ISIS targets in Syria, the Pentagon said on Monday, in ongoing operations that mark the opening of a new, far more complicated front in battle against the militants.
"I can confirm that U.S. military and partner nation forces are undertaking military action against ISIL in Syria using a mix of fighter, bomber and Tomahawk Land Attack Missiles," Rear Admiral John Kirby, Pentagon press secretary, said in a statement.
"Given that these operations are ongoing, we are not in a position to provide additional details at this time."
Around 20 targets were hit during the attacks, a U.S. official said.
The official said some of the strikes employed Tomahawk missiles launched from at least one U.S. ship at sea.
The United States informed Syria’s U.N. representative on Monday that Islamic State targets
would be hit in the Syrian city of Raqqa, Syrian state television reported on today.
The television broadcast the news in a headline bar and cited Syria’s Foreign Ministry as the source.
Dozens of ISIS fighters were killed or wounded in air strikes on the Syrian city of
Raqqa and surrounding areas, a group that tracks the war said on Tuesday.
"There are tens of wounded and dead," Rami Abdulrahman, head
of the Syrian Observatory for Human Rights, said. The Observatory gathers information from a network of activists on the ground.
The Pentagon earlier said the United States and partner nations were carrying out the first air strikes against Islamic State targets in Syria.
Among the futuristic weaponry deployed against ISIS by the US were the $143m F-22 stealth Raptors - which are being used for the first time in combat.
The strikes are understood to be targeting the ISIS command and control sites in Syria, with the stronghold town of Raqqa particularly hard hit.
Training camps and logistical sites have also been pounded in the strikes.
The airstrikes are a major escalation of the US campaign against ISIS.
They show that US President Barack Obama is prepared to use American military might to confront the militants.
Calls are increasing for the US and other Western nations to send ground troops in to Iraq to help fight back the militants, who have overwhelmed the Iraqi Army.
The recent beheadings of US and British hostages has ramped up the pressure on President Obama and British Prime Minister David Cameron to act.
Saudi Arabia, the United Arab Emirates, Jordan and Bahrain were involved in U.S. air strikes launched in Syria against ISIS, a U.S. official said, although their exact roles in the military action were unclear.
Qatar played a supporting role in the air strikes, the official said.
There are reports that the US and allied airstrikes on ISIS have also hit targets in northern Iraq.
The US informed Syria that it would be entering its airspace to hit the militants who occupy larges parts of the country.
The strikes have reportedly included targeted missile attacks, launched from US Navy vessels in the Gulf.
Former prime minister Tony Blair has said Britain and its allies must be prepared to send in ground troops to defeat ISIS.
The former PM warned that air strikes alone are not enough to smash the advance of ISIS.
Speaking to the BBC, he said: "Unless you're prepared to fight these people on the ground, you may contain them but you won't defeat them."
He added: "The problem is not that we're facing a fringe of crazy people, a sort of weird cult confined to a few fanatics”
His comments are likely to spark controversy with people still angry over Britain's involvement in the 2003 Iraq war.
Barack Obama has been reluctant to deploy US military might in the Middle East and made withdrawing troops from Iraq a priority of his presidency.
But, faced with the threat of a region-wide conflict initiated by ISIS, Obama has taken decisive action.
Commentators have warned, however, that US air power alone cannot defeat the ISIS fighters, who are firmly entrenched in large parts of Syria and Iraq.
The White House is reportedly considering working with Iran to combat ISIS.
The powerful militant organisation holds territory on the border with Iran, Iraq, Syria and Turkey.
Concerns have been raised that Tehran might try to trade concessions over its nuclear programme from the US in return for support against ISIS.
The White House has denied that any such deal exists.
Britain said on Tuesday that no final decision had been made over whether to join air strikes
launched by the United States and several Gulf Arab allies on Islamic State strongholds in Syria.
A spokeswoman at the Ministry of Defence said discussions were still ongoing.
The office of British Prime Minister David Cameron said Britain was not currently part of the action against Islamic State fighters who have seized large expanses of territory in Iraq and Syria.
The airstrikes were carried out by USAF and US Navy aircraft, with Tomahawk missiles fired from ships in the Persian Gulf and Red Sea.
The strikes were ordered by General Lloyd Austin, the commander of US forces in the Middle East and South Asia.
They were authorised by President Barack Obama.
The US has already launched 200 airstrikes in Iraq. The expansion of the strikes into Syria is an widening of the use of military force against ISIS.
An Israeli Patriot missile shot down a Syrian aircraft that flew into Israeli-controlled
airspace on Tuesday, the military said, without disclosing the type of plane it intercepted.
"Moments ago a Syrian aircraft infiltrated Israeli airspace.
The IDF (Israel Defense Forces) intercepted the aircraft in mid-flight, using the Patriot air defence system. The circumstances of the incident are being reviewed," a military statement said.
Israel Radio said the aircraft was a drone and was shot down over the Israeli-occupied Golan Heights, where fighting from Syria’s civil war has occasionally spilled over. Israeli Army Radio said it may have been a Syrian warplane.
Shadow business secretary Chuka Umunna said it was "inconceivable" that British Prime Minister David Cameron could commit to joining the US airstrikes against ISIS without seeking the approval of Parliament.
He said Labour would apply the same criteria as to last year's planned strikes on Syria - which MPs voted down - to any new proposal.
He told Sky News: "Isis need to be eliminated. What they are doing in the region is evil, is terrible.
"Obviously the Prime Minister hasn't determined yet that the UK should get involved.
"If that is something he does, the Labour Party will apply the same criteria to whether or not we choose to support the intervention as we applied to the proposed Syrian action last year - is there a legal basis to intervene, is there a plan for intervention, and, importantly as well, learning the lessons from Iraq, is there a plan for what happens after?
"It is inconceivable that the Prime Minister could press on with air strikes frankly without consulting Parliament and seeking proper consultation with Parliament."
A US military drone has crashed in the northern Syrian city of Raqqa - ISIS claim.
The drone is believed to have crashed into a communications tower.
Fragments of the aircraft were collected and loaded into the back of a van.
It comes as US and Arab air and missile strikes have pounded ISIS strongholds and training bases in Syria.
Pressure is rising on US President Barack Obama to commit US ground forces to fighting ISIS.
Commentators have warned that airstrikes alone will merely disrupt, rather than destroy the militants' forces in the region.
Should Britain join the airstrikes on ISIS?
To recap: The US and Arab partner nations have launched airstrikes on ISIS targets in Syria.
The move is a significant escalation of America's military campaign against the militants - who hold swathes of territory across the region.
Around 20 targets have been hit, including ISIS training and logistics sites.
The strikes will increase pressure on US President Barack Obama to commit US ground troops to fighting ISIS.
In Britain, Labour's Chuka Ummuna has warned that it is 'inconceivable' that Prime Minister David Cameron will commit Britain to joining in with the airstrikes without the approval of Parliament.
Meanwhile, Israeli forces say they have shot down a Syrian fighter jet which strayed into their air space.
Bob Baer, a former CIA analyst who is currently liaising between the US government and Sunni tribes in northern Iraq, said bombarding ISIS will ultimately end in failure.
He told the BBC: "We can decapitate Isis, we can degrade them, but this is not going away, it's not going to lessen the civil war in Iraq or the civil war in Syria.
"The way the Sunnis look at it - I'm not talking about Isis - is we're siding with Iran, (Syrian president Bashar al-Assad) and the Alawites.
"They will look at it as if we're entering the civil war. There will be an indeterminable outcome to this, a blowback if you like.
"I can't tell you where it's going to be - it could be Jordan, it could be Lebanon - but we've not heard the end of this so this is a very risky move bombarding Raqqa."
Syria’s Western-backed National Coalition opposition group has welcomed airstrikes by the United States and its Arab allies on ISIS strongholds in Syria.
The group said the strikes would strengthen its struggle against President Bashar al-Assad - whose forces have been engaged in a civil war that has claimed thousands of lives.
"This will make us stronger in the fight against Assad," Monzer Akbik, special envoy to the president of the coalition, said.
"The campaign should continue until the Islamic State is completely eradicated from Syrian lands."
Former foreign secretary Jack Straw said he was not against the principle of "proportionate and sensible" British involvement in military action against ISIS.
He said, however that operations in Syria required "some kind of consent" from the Syrian government.
The Labour MP told the BBC Radio 4 Today programme: "We're part of the Western alliance, we have key interests - direct and indirect - in the region, so in principle we should be involved provided the circumstances are right.
"I'm sorry if that sounds qualified but if there is a clear proposition from the British Government for British military involvement, which is discussed in detail with Ed Miliband and shadow foreign secretary Douglas Alexander, I know that it will be given a very sympathetic hearing as it will do from the parliamentary Labour Party."
British Foreign Secretary Philip Hammond has previously said Britain will play a "leading role " in the coalition - although the signs are that the UK is more likely to join air strikes against ISIS in Iraq rather than in Syria.
While Downing Street has said nothing has been ruled out, Mr. Hammond has said there would be significant military, legal and technical differences in mounting strikes on Syrian territory.
In particular, strikes on IS in Iraq would be conducted at the invitation of the government in Baghdad, while Britain has ruled out any co-operation with the Syrian regime of President Bashar Assad.
France, which has already joined the US in carrying out attacks on ISIS forces in northern Iraq, has ruled out extending its action into Syria.
The Syrian foreign ministry is preparing to make an "important statement", state TV has said.
It comes after US led coalition launched air strikes on ISIS targets in the north of the country.
Stay with us for further updates.
Air strikes by US-led coalition forces in Syria killed 30 fighters from al-Nusra Front and eight civilians including children, a group monitoring the war said on Tuesday.
The strikes targeted a residential building in Aleppo province used by Nusra Front, said Rami Abdulrahman, who runs the Britain-based Syrian Observatory for Human Rights.
The United States said earlier on Tuesday its forces had carried out eight strikes against al Qaeda-affilated militants west of Aleppo.
A man inspects the damage in a communication station which ISIS fighters say a US drone crashed into in Raqqa, norther Syria.
The US and several Gulf Arab allies launched air and missile strikes on Islamic State strongholds in Syria today.
Fighter jets, drones and ship-launched Tomahawk missiles were all reported to have been used in the strikes.
NATO said on Tuesday it was not involved in US-led strikes on Islamic State targets in Syria.
NATO's 28 member states includes Britain.
"There is no NATO involvement," an alliance official said.
The US and Arab allies hit ISIS targets including training camps, headquarters and weapon supplies in northern and eastern Syria in dozens of air and missile strikes today.
The special relationship between the US and Britain has come under fresh scrutiny following today's airstrikes on ISIS targets in Syria.
The lack of British involvement the military action shows President Barack Obama's willingness to act without UK support.
David Cameron failed to win the backing of Parliament to support US airstrikes on Syria last year.
It was the first time in decades that a British Prime Minister was unable to provide military support for a joint operation with the Americans.
Commentators have claimed that the White House no longer believes the US can rely automatically on British support when taking military action.
BBC political editor Nick Robinson illustrated this feeling when he tweeted this morning.
This video claims to show US-led airstrikes on ISIS targets in Syria.
The footage, which was shot at night, shows a series of explosions, apparently caused by missile strikes.
The US and its Arab allies, used aircraft, drones and missiles to strikes around 20 ISIS targets.
These includes training bases, logistics and weapons dumps.
The Syrian government said on Tuesday it had received a letter from US Secretary of State John Kerry telling it the United States and its allies planned to attack ISIS in Syria.
"The foreign minister received a letter from his American counterpart via the Iraqi foreign minister, in which he informed him that the United States and some of its allies would target (Islamic State) in Syria," the foreign ministry said in a statement. "That was hours before the raids started."
In the statement read out on state TV, the Syrian government said it would continue to attack Islamic State in Raqqa and Deir al-Zor - areas of eastern and northern Syria that were hit in the US-led air strikes on Tuesday.
The Syrian government said coordination with the Shi’ite-led government in Baghdad was continuing at its "highest levels".
This video shows US Navy jets taking off to strike ISIS targets deep inside Syria.
Around 20 sites were hit, including training bases, logistics and weapons dumps.
The strikes, which the US carried out in partnership with Arab allies, is a major escalation in the battle against ISIS.
Airstrikes will weaken ISIS but not destroy it, a security analyst has warned.
Shashank Joshi, senior research fellow at military think tank the Royal United Services Institute (RUSI), said in the absence of ground troops the US-led campaign would be limited to "applying pressure" on the group.
He said the first wave of strikes in Syria were an important development in the fight against IS.
"Given IS's headquarters and most of its wealth-producing assets are in Syria, it's extremely important that they are targeted across both countries.
"In order to weaken and eventually defeat IS you have to take them on on both sides of what is a very porous border."
The United Nations refugee agency said on Tuesday that it was making contingency plans for all 400,000 inhabitants of the Syrian Kurdish town of Kobani to flee into Turkey to escape the advance of Islamist militants.
Some 138,000 Syrian Kurdish refugees have entered Turkey in an exodus that began last week, and two border crossing points remain open, the UN High Commissioner for Refugees said.
"We are preparing for the whole population fleeing into Turkey. The population of Kobani is 400,000," UNHCR chief spokeswoman Melissa Fleming told a news briefing in Geneva.
"We don’t know, but we are preparing for that contingency."
The death toll from US strikes on al-Nusra fighters in northern Syria has risen to 50, a monitoring group said on Tuesday.
The Syrian Observatory for Human Rights said most of those killed in the strikes, which targeted fighters from the Nusra Front in the northern Idlib area, had been non-Syrians.
The strikes on the Front come alongside attacks on ISIS bases in the region.
To recap: The US and Arab partner nations have launched airstrikes on ISIS targets in Syria.
The move is a significant escalation of America's military campaign against the militants - who hold swathes of territory across the region.
Around 20 targets have been hit, including ISIS training and logistics sites.
The strikes will increase pressure on US President Barack Obama to commit US ground troops to fighting ISIS.
In Britain, Labour's Chuka Ummuna has warned that it is 'inconceivable' that Prime Minister David Cameron will commit Britain to joining in with the airstrikes without the approval of Parliament.
Meanwhile, Israeli forces say they have shot down a Syrian fighter jet which strayed into their air space.
The UN is preparing for 400,000 Kurdish refugees in Syria to flee into Turkey as ISIS continues to advance.
It has been revealed that the Syrian's were warned of the US-led strikes on ISIS in a letter from American Secretary of State John Kerry - which was received hours before the raids began.
Residents are fleeing the Syrian city of Raqqa after US warplanes struck positions held by ISIS fighters.
"There is an exodus out of Raqqa as we speak," one witness said.
"It started in the early hours of the day after the strikes. People are fleeing towards the countryside."
ISIS bases have been attacked across northern Syria by US-led coalition forces.
This dramatic footage shows Tomahawk missiles being launched against ISIS from the deck of a US warship.
The video shows crew on the bridge of the vessel watching on as the missiles take off into the night sky - headed for militant targets in Syria.
The footage emerged after a US-led coalition pounded ISIS-held territory in the war-torn country.
US President Barack Obama is due to make a statement following American-led airstrikes on ISIS militants in Syria.
He will speak from the White House before departing for New York at 2.20pm to attend the United Nations climate meeting.
The US and Arab allies began bombing in Syria for the first time on today, pursuing a campaign against ISIS in a war at the heart of the Middle East.
ISIS has vowed revenge for the attacks in Syria.
This live blog is now closed.
To recap on today's events: The US and Arab partner nations have launched airstrikes on ISIS targets in Syria.
The move is a significant escalation of America's military campaign against the militants - who hold swathes of territory across the region.
Around 20 targets have been hit, including ISIS training and logistics sites.
The strikes have increased pressure on US President Barack Obama to commit US ground troops to fighting ISIS.
In Britain, Labour's Chuka Ummuna has warned that it is 'inconceivable' that Prime Minister David Cameron will commit Britain to joining in with the airstrikes without the approval of Parliament.
Meanwhile, Israeli forces say they have shot down a Syrian fighter jet which strayed into their air space.
The UN is preparing for 400,000 Kurdish refugees in Syria to flee into Turkey as ISIS continues to advance.
It has been revealed that the Syrian's were warned of the US-led strikes on ISIS in a letter from American Secretary of State John Kerry - which was received hours before the raids began.
