Prime Minister Malcolm Turnbull has assured the nation that Australia is “not at war” as he backed US airstrikes against the Syrian government.

Mr Turnbull said the US bombardment of a Syrian-government controlled airfield on Friday morning Australian time was a “calibrated, proportionate and targeted response” to an earlier chemical weapons attack by Bashar al-Assad’s government.

“But we are not at war with the Assad regime and United States have made it clear that they are not seeking to overthrow the Assad regime,” he said. 

Confirming that Australia was not involved in Friday’s action, the Prime Minister said the airstrikes would send a “strong message” following the “war crime” carried out by the Assad regime.

“The effect of the American response has been to reduce the ability of the Syrian Government to deliver chemical weapons in the shocking manner in which they did a few days ago,” he said.

On Friday morning, US President Donald Trump ordered the launch of 59 Tomahawk missiles at the al-Shayrat airfield, near Homs, bringing the US into direct conflict with the Assad regime for the first time.

Mr Turnbull said Australia had been briefed prior to the attack as a Coalition partner.

Malcolm Turnbull backed US airstrikes in Syria on Friday. Photo: AAP

He also blamed Russia, a key ally of the Assad government, for an “impasse” at the United National Security Council over Syria, and questioned President Assad’s involvement in any future solution.

“The fact is … there is a solemn obligation on Russia to play its part in bringing this conflict to an end,” he said.

What we know about the attack

About 10.45am (AEST) Friday, the US fired 59 Tomahawk missiles at the al-Shayrat airfield, a Syrian military site close to Homs.

US officials said the missiles were fired from two warships in the Mediterranean Sea.

Russian forces were notified of the attack in advance, the Pentagon said.

The Syrian army said the airstrikes killed six people and caused “big material losses”, accusing the US of “blatant aggression” against the airbase.

Speaking at his Mar-a-Lago resort, President Donald Trump said the airstrikes had been launched in response to a “horrible chemical weapons attack on innocent civilians”.

Mr Trump said it was in the United States’ “national security interests” to deter the Syrian government from using deadly chemical weapons.

“Years of previous attempts at changing Assad’s behaviour have all failed and failed very dramatically,” he said.

The Kremlin issued a strong statement in response to the attacks, condemning the US move as “aggression against a sovereign nation” that would do “significant damage to US-Russia ties”.

Moscow claimed Syria did not have chemical weapons, meaning the strikes had been launched on a “invented pretext”.

Russian President Vladimir Putin believed the attack was aimed at deflecting world attention from civilian deaths in Iraq, the statement said, and that they would hamper efforts to create an international coalition to defeat Islamic State.

The Russian strongman is now demanding the UN Security Council convene without delay.

“Russia will first of all demand an urgent meeting of the UN Security Council. This can be regarded as an act of aggression on the part of the US against a UN state,” said Senator Victor Ozerov, chairman of the Russian Federation Council’s Committee on Defense and Security.

A statement on Syrian state TV said only that “American aggression” had targeted a Syrian military base with a “number of missiles”.

Talal Barazi, Governor of Homs, near where the airstrike occurred, said the airstrikes had served the goals of “armed terrorist groups” and Islamic State, Reuters reported, according to Reuters.

“Syrian leadership and Syrian policy will not change. This targeting was not the first and I don’t believe it will be the last,” he said.

In the US, senior Republican politicians welcomed the military strike.

Senators John McCain and Lindsey Graham said it showed the US would “no longer stand idly by as Assad, aided and abetted by Putin’s Russia, slaughters innocent Syrians with chemical weapons and barrel bombs”.

Democrat Adam Schiff, the Ranking Member of the House Intelligence Committee, said the strike may “deter” future use of chemical weapons, but noted that it had not been approved by the Congress.

Former Secretary of State and 2016 Democratic presidential nominee Hillary Clinton had earlier called on the US to bomb Syrian airfields.

Israeli Prime Minister Benjamin Netanyahu said Mr Trump had “sent a strong and clear message” that “the use and spread of chemical weapons will not be tolerated”.

Trump’s change of heart

President Trump had previously expressed previous misgivings about the becoming entangled in the Syrian conflict.

His attitude changed following the Syrian government’s use of “deadly nerve agent” that led to a “slow and brutal death” for men, women and children.

“Even beautiful babies were cruelly murdered in this barbaric attack,” he said.

Mr Trump said Syria had violated its obligations and ignored the urgings of the United Nations Security Council.

“Years of previous attempts at changing Assad’s behaviour have all failed and failed very dramatically,” he said.

The President did not announce the attacks in advance, though he and other national security officials ratcheted up their warnings to the Syrian government throughout the day on Thursday.

In 2013, President Obama decided not to launch airstrikes in response to the use of chemical weapons by the Assad regime, despite earlier describing such action as a “red line”.