The Pentagon said it tracked the jets involved in the chemical strike on Khan Shaykhoun after identifying the crater left at the site.

Officials released a map of the reported journey made by the jets.

Image source, Pentagon

Image source, Pentagon

Several people died at the airbase targeted by the US, Al Shayrat, the governor of Homs province where the base is located told AFP.

"There are martyrs, but we don't yet know the number either of martyrs or of wounded," Talal Barazi said.

Mr Barazi said that Syrian forces operating out of the base were targeting the so-called Islamic State.

Image source, Pentagon

The Department of Defense has just tweeted a video of their missile launches against targets in Syria.

Israeli Prime Minister Benjamin Netanyahu has issued a statement saying he "fully supports" the strikes.

"In both word and action, President Trump sent a strong and clear message today that the use and spread of chemical weapons will not be tolerated.

"Israel fully supports President Trump's decision and hopes that this message of resolve in the face of the Assad regime's horrific actions will resonate not only in Damascus, but in Tehran, Pyongyang and elsewhere." 

BBC State Department Correspondent Barbara Plett Usher has tweeted six takeaways from Trump's sudden shift to aggression on Syria.

Speaker of the House Paul Ryan released the following statement on Twitter:

Democrat representative Barbara Lee has called on Speaker of the House Paul Ryan to bring the military action to a vote.She was the only one who voted against a 2001 law that allowed then-president George W Bush to use military action against perpetrators of the 9/11 attacks.

Anthony Zurcher
BBC North America reporter

The man who was thought to be a neo-isolationist is now, just months into his presidency, projecting US military force abroad to enforce international norms and punish human rights abuses.

If the president’s foreign policy outlook can shift so dramatically in just a few days, if not hours, will allies and adversaries interpret this as a sign of flexibility or incoherence? 

A cruise missile strike is a low-risk form of military action, but it also is of limited effectiveness. A White House official described this as a warning shot across Mr al-Assad’s bow. 

If the Syrian president continues to use chemical weapons or conduct conventional attacks that result in significant civilian casualties, will the US escalate its military intervention or back down and risk appearing weak?

Thursday night was Mr Trump’s first significant foreign policy challenge, and it appears to have dramatically changed his outlook, his rhetoric and his resulting actions. 

The candidate who constantly spoke of putting America first ended his brief remarks Thursday night by calling for God’s blessings not just for his nation but for the “entire world”.

This strike – and this change of attitude – may simply be a one-off event. Or, perhaps, an unlikely globalist has been born.

The announcement of the strikes against Syria happened moments after Chinese President Xi Jinping and his wife Peng Liyuan left Trump's Mar-a-Lago club, following dinner with the President and First Lady.

Image source, AFP/Getty Images

BBC America anchor Katty Kay and the Washington Post's China correspondent Emily Rauhala analyse the air strike's timing.

Chuck Schumer, the Senate minority leader of the Democrats and a vocal critic of Donald Trump, has released the following statement:"Making sure Assad knows that when he commits such despicable atrocities he will pay a price is the right thing to do."It is incumbent on the Trump administration to come up with a strategy and consult with Congress before implementing it. I salute the professionalism and skill of our Armed Forces who took action today."

Image source, Chuck Schumer

US Secretary of State Rex Tillerson, who also addressed reporters, said that Russia was either "complicit" in the Syrian government's chemical attack or was "incompetent" by failing to secure and remove chemical weapons from Syria. He added that the US cruise missile attack was a "proportionate" response and showed that President Trump was "prepared to take decisive action to respond to heinous acts".

Trump's national security adviser HR McMaster also addressed reporters at Mar-a-Lago, telling them that the president was given three options for strikes against the Assad regime.

Trump told advisers to focus on two and made a decision on Thursday, according to McMaster. It was "not a small strike," McMaster said.

He added: “Obviously, the regime will retain a capacity to commit mass murder with chemical weapons beyond this airfield.” 

Jon Sopel
BBC North America Editor

Rarely has a policy changed so far and so quickly, and rarely has it been acted upon so swiftly. 

When President Trump came to office, the Syrian leader was seen as a useful ally in the fight against so-called Islamic State. All talk of regime change stopped. 

But the chemical weapons attack changed all that. Within two days of the attack, the US has reversed its view on President Assad, identified targets and struck. 

What we don't know is whether this is a one-off act of retaliation, or the start of something more prolonged against the Assad regime. 

And where it leaves relations with Syria's strong ally, Russia.

US Secretary of state Rex Tillerson said that while US officials did warn Russian forces in Syria about the strikes they did not seek approval from the Russians, according to CNN correspondent Jeff Zeleny.

The strike targeted Shayrat airfield, a Syrian military airbase near the city of Homs.

The Pentagon said in a statement that the 59 Tomahawk missiles targeted aircraft, hardened aircraft shelters, petroleum and logistical storage, ammunition supply bunkers, air defense systems, and radars.

Image source, Pentagon

A Pentagon official said about 50 Tomahawk cruise missiles were fired from US Navy destroyers in the eastern Mediterranean at a Syrian air base.  

Some US media are reporting that the two were the USS Porter and USS Ross.

Image source, AFP

Image source, AFP

Pentagon Spokesman Captain Jeff Davis issued a statement in which he confirmed that US officials warned Russian counterparts ahead of the strikes over a "deconfliction line".  

Here's the statement in full.

BBC Washington reporter Laura Bicker parses Trump's decision.