Trump orders missile strikes in Syria following chemical attack

US President Donald Trump ordered a massive military strike on a Syrian air base, in retaliation for a "barbaric" chemical attack he blamed on President Bashar al-Assad, declaring he acted in America's "vital national security interest".

In a sharp escalation of the US military role in Syria, two US warships fired dozens of cruise missiles from the eastern Mediterranean Sea at the airbase controlled by Syrian President Bashar al-Assad's forces in response to the poison gas attack in a rebel-held area on Tuesday, US officials said.

The gas attack killed at least 70 people, many of them children, in the Syrian town of Khan Sheikhoun, in the Idlib province.

Trump, who for years signalled he was comfortable with Assad remaining in power, pointed the finger at Assad for this week's chemical attack. He said that the attack had “changed his attitude toward Syria and Assad very much,” and called on the international community to “join us in seeking to end the slaughter and bloodshed in Syria and also to end terrorism of all kinds and all types”, leaving it unclear whether the US objective was retaliation for the sarin gas assault, destruction of Assad’s chemical stockpiles, or a push to oust Assad from power.

The Syrian government has denied it was behind the attack and blames the opposition fighters of stockpiling chemical weapons.

In a brief televised address delivered hours after the UN Security Council failed to agree on a probe into the apparent chemical attack, Trump confirmed the first American targeted strike against Assad's regime.

Tonight I ordered a targeted military strike...... pic.twitter.com/3nUzrdiGzX

— President Trump (@POTUS) April 7, 2017

Fifty-nine Tomahawk missiles were launched from the USS Porter and USS Ross around 8:40pm local time (1:40am CET), striking multiple targets - including the airstrip, aircraft and fuel stations - on the Shayrat Air Base, which the Pentagon says was used to store chemical weapons.

The attack was a "one-off," a US defence official told Reuters news agency, meaning it was expected to be a single strike with no current plans for escalation.

US Secretary of State Rex Tillerson said the strike did not mean the wider US policy on Syria had changed.

"This clearly indicates the President is willing to take decisive action when called for," he told reporters. "I would not in any way attempt to extrapolate that to a change in our policy or our posture relative to our military activities in Syria today. There has been no change in that status."

Syrian officials said at least seven people were killed and nine wounded in US missile attack, which caused extensive damage to the base. It called the attack an “aggression that undermines Damascus' counter terrorism operations.”

US officials said they informed Russian forces ahead of the missile attacks and that there were no strikes on sections of the base where Russians were present. But they said the administration did not seek Moscow's approval.

The Kremlin, which backs Bashar al-Assad, has condemned the strike.

Dmitry Peskov, spokesman for Russian President Vladimir Putin, called it "an act of aggression against a sovereign nation".

Russia has warned of potential "negative consequences" if Washington strikes Syria.

In response to the US strike on a Syrian air base, the Russian foreign ministry said that Moscow was suspending a memorandum with the US to prevent incidents and ensure flight safety. Under the memorandum, signed after Russia launched an air campaign in Syria in September 2015, Russia and the US had exchanged information about their flights to avoid incidents in the crowded skies over Syria.