The US has defended its cruise missile strike against a Syrian government airbase, threatening that “we are prepared to do more” if necessary.

US ambassador Nikki Haley made the remarks in an emergency meeting of the Security Council on Friday, declaring that the US would not “stand by” while chemical weapons were used on civilians.

The session was called to discuss the ramifications of US President Donald Trump’s decision to retaliate to a suspected sarin and chlorine attack in the rebel village of Khan Sheikhoun in Idlib province, which killed at least 80 people.

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Ms Haley was defiant that the US had acted appropriately in striking the regime for crossing the “red line” of chemical weapons use – something Mr Trump’s predecessor Barack Obama talked about after a suspected regime sarin gas attack killed hundreds of people in rebel-held Ghouta in 2013.

“[Syrian President Bashar] Assad did this [the Khan Sheikhoun attack] because he thought he could get away with it. He thought he could get away with it because he knew Russia had his back. That changed last night,” she said.

Ms Haley went on to repeat words she used on Thursday, just before Mr Trump ordered the action.

“When the international community fails in its duty to act collectively, there are times when states are compelled to take their own action. The use of chemical weapons against innocent civilians is one of those times.”

The strike on al-Shayrat airbase near the central city of Homs, which killed at least seven people, marked the first direct US act of hostility against President Bashar al-Assad in more than six years of war.

The deputy envoy of Syria’s ally Russia, Vladimir Safronkov, asked Ms Haley not to “insult” his country, reiterating the Kremlin’s assertion that the missile attack near Homs was “illegitimate” and the move could have severe consequences for both regional and international stability.

He described the strike as an “attempt to distract attention from the many victims amongst the peaceful population in Iraq and Syria caused by unilateral actions”.

In pictures: US missile strike against Syria Show all 7 1 /7 In pictures: US missile strike against Syria In pictures: US missile strike against Syria The guided-missile destroyer USS Porter (DDG 78) launches a tomahawk land attack missile in the Mediterranean Sea AP In pictures: US missile strike against Syria The United States military launched at least 50 tomahawk cruise missiles at al-Shayrat military airfield near Homs, Syria, in response to the Syrian military's alleged use of chemical weapons in an airstrike in a rebel held area in Idlib province EPA In pictures: US missile strike against Syria Shayrat airfield in Syria Getty Images In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria President Donald Trump speaks at Mar-a-Lago in Palm Beach, Fla., after the US fired a barrage of cruise missiles into Syria in retaliation for this week's gruesome chemical weapons attack against civilians AP In pictures: US missile strike against Syria Syria's President Bashar al-Assad Reuters

Syrian ambassador Bashar Jaafari also said that his government viewed the strike as “illegal”, motivated by “propaganda” and “unobjective data”.

Both Damascus and Moscow have denied the regime used chemical weapons in Khan Sheikhoun, maintaining that the casualties were caused by gases released after an al-Qaeda-affiliated ammunitions depot was hit by conventional munitions in a government air raid.

The shock US decision to launch a strike against a Syrian regime target has further complicated the already dazzlingly complex Syrian civil war.

The UN’s envoy to Syria, Staffan di Mistura, said on Friday that his office was in “full blown crisis management mode”, with three years of sustained peace efforts potentially on the line.

The White House has stressed that the 59 Tomahawk missiles launched at al Shayrat airbase – which a local resident described as causing “massive blasts” – were a “necessary and appropriate” warning shot in retaliation for the alleged chemical weapons attack.

Yet fears of further US direct military action – carried out without consultation from Congress – are building, both inside Syria and across the world.

“You will not be able to bomb your way to peace in Syria,” Senator Ben Cardin, the top Democrat on the Senate Committee on Foreign Relations, told CNN on Friday.

“Syrians must work out their problems,” Mr Cardin said. “President Assad must be held accountable for war crimes. He’s lost credibility as a leader. He must leave the presidency. This is not just what America thinks, but the international community.”

The new US administration had previously appeared content to let Turkey take the lead in peace negotiations with Russia, Iran and the Syrian government, focusing its military efforts in the country on defeating Isis and al-Qaeda rather than Mr Assad’s removal from power.

Since the fall of Aleppo in December 2016, and Mr Trump’s arrival in office, most Western players in Syria’s war have operated on the understanding that the best outcome rebel fighters can hope for is free elections in which the embattled ruler agrees to step down.

The strikes were cautiously welcomed by the US’s Western allies, including the UK, as a “proportionate” response to Mr Assad’s alleged use of chemical weapons.

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While Mr Assad has acted with “impunity” and is “the greatest war criminal of all”, UK ambassador Matthew Rycroft told the Security Council, “a diplomatic solution must be found to the crisis”.

The long-term prospects for peace in Syria remain as grim as ever. While a ceasefire has technically been in place across Syria since the end of December between the moderate opposition and the government, both sides have continued to launch attacks, and a fifth round of peace talks in Geneva ended at an impasse at the end of last month.

The US, UK and French representatives to the UN on Thursday called for a vote on a new resolution which would impose sanctions on “those responsible” for the chemical attacks on Khan Sheikhoun.