Washington, April 8: Nikki Haley, the US envoy to the UN, has defended her country’s action of firing 59 Tomahawk missiles on a Syrian airbase that killed several people. She also severely criticised Russia for allowing Syria's leader to accumulate chemical weapons.

Haley warned the US was "prepared to do more" in response to Syria's use of chemical weapons that killed many civilians, in her address at a special UN session after the strike on the Shairat airbase.  The meeting took place as the US and allies press for a resolution condemning the Assad regime for the bombing. Russia is likely to veto the resolution.

Haley delivered a sharp rebuke to Russia for its support to Syria, saying President Bashar al Assad regime was "playing Russians for fools… telling them that there were no chemical weapons".

"The US took a very measured step last night (Thursday night)," she said.

"We are prepared to do more. But we hope that will not be necessary. It is time for all civilised nations to stop the horrors that are taking place in Syria and demand a political solution."

"The joint investigative mechanism has found beyond any doubt that the Syrian regime has used chemical weapons against its own people multiple times," Haley said.

She said that Moscow was "incompetent" in removing the chemical weapons and the Assad regime's crimes against innocent civilians.

She said Russia was "knowingly allowing chemical weapons to be used in Syria".

"Assad thought he could get away with it because he knew Russia had his back."

Thursday's strike was the first direct military action taken by the US against the Assad regime. It represents a dramatic escalation of the US military campaign in the region, and could be interpreted by Syria as an act of war.

Russia's envoy to the UN             Vladimir Safronkov slammed the US action, calling it "a flagrant violation of international law and an act of aggression".

Haley said "there are times when states are compelled to take their own action" and that preventing the spread and use of chemical weapons was in the US' "vital national security interest".

"We were fully justified in doing so."

Safronkov warned that "the consequences of this for regional and international stability could be extremely serious".

Haley then yielded the floor to Syria's Deputy UN Ambassador Mounzer Mounzer who maintained that Syria "would never use such weapons in any of its operations against armed terrorist groups".

"Let me stress that it is well known that those weapons have been used and stockpiled in many parts of Syria by terrorist armed organisations in cooperation or rather with a wink and a nudge by some ruling regimes in the region and outside, including Turkey, Saudi Arabia, Qatar and some European states," Mounzer said.

"They completely ignore all the facts and documented information on the use of chemical weapons by terrorists in many parts of the Syrian Arab Republic."

Bolivia's ambassador to the UN Sacha Sergio Llorenti Soliz criticised the US of acting as "prosecutor", "judge" and "jury" in Syria.

"The US not only unilaterally attacked, but while we were discussing here and demanding the need for an independent investigation an impartial investigation, complete investigation into the attacks, the US has become that investigator, has become the prosecutor, has become the judge, has become the jury," said Soliz.

UN Secretary General Antonio Guterres said all parties must remember their "shared duty to uphold international standards of humanity".

Guterres appealed for "restraint to avoid any acts that could deepen the suffering of the Syrian people". He said there was "no other way to solve the conflict than through a political solution".