Syrian president Bashar al-Assad told a group of Russian politicians on Sunday that Western missile strikes on his country were an act of aggression, Russian news agencies reported.

Russian politicians met with Mr Assad after the United States, France and Britain launched 105 missiles in retaliation for a suspected poison gas attack in Syria a week ago, targeting what the Pentagon said were three chemical weapons facilities, including a research and development centre in the Barzeh district of Damascus and two installations near Homs.

The bombing was the biggest intervention by Western countries against Mr Assad and his superpower ally Russia, but the three countries said the strikes were limited to Syria’s chemical weapons capabilities and not aimed at toppling Mr Assad or intervening in the civil war.

Russian news agencies quoted politicians as saying Mr Assad was in a “good mood” and had praised the Soviet-era air defence systems used by Syria to help to repel the Western attacks.

The supply of Russian air defence systems was not discussed, agencies reported, but Mr Assad accepted an invitation to visit the Siberian region of Khanty-Mansi in Russia. It was not clear when the visit would take place.

Palestinians burn a US flag during a protest against air strikes in Damascus, in Gaza city April 15, 2018. Photograph:Mohammed Salem/Reuters

US president Donald Trump called the operation a success, tweeting “Mission accomplished”.

The US ambassador to the United Nations, Nikki Haley, said at an emergency meeting of the UN Security Council that Mr Trump told her that if Syria uses poisonous gas again, “The United States is locked and loaded.”

Russian Foreign Minister Sergei Lavrov said the strikes were “unacceptable and lawless.”

Syrian state media called them a “flagrant violation of international law,” while Iranian Supreme Leader Ayatollah Ali Khamenei called it a crime and the Western leaders criminals.

Russia had promised to respond to any attack on its ally, but the Pentagon said no Russian air defence systems were used. Syria fired 40 unguided surface-to-air missiles - but only after the Western strikes had ended, the Pentagon said.

Backlash

British prime minister Theresa May described the strike as “limited and targeted,” with no intention of toppling Assad or intervening more widely in the war.

Ms May has faced a backlash from MPs, with Jeremy Corbyn calling for a war powers act to give parliament more scrutiny over military action.

Appearing on BBC One’s The Andrew Marr Show, the Labour leader questioned the legal basis for the UK joining the US and France in air strikes in response to the chemical weapons attack in Douma.

Mr Corbyn said Parliament should have been given a vote ahead of the strikes.

“I think what we need in this country is something more robust like a War Powers Act so that governments do get held to account by Parliament for what they do in our name.”

The Labour leader warned of an escalation in a “proxy war” between the US and Russia. He said chlorine has been used by “a number of parties in the conflict” in Syria as a weapon.

Mr Corbyn said that if Britain wants to “get the moral high ground around the world” it must abide by international law for taking military action.

“Where is the legal basis for this?” he said.

Foreign secretary Boris Johnson said “finally the world has said enough is enough” as he defended the “proportionate” action.

“There is no proposal on the table at the moment for further attacks because so far — thank heavens — the Assad regime has not been so foolish to launch another chemical weapons attack.”

USS Monterey fires a Tomahawk land attack missile on April 14th, 2018. Photograph: US Department of Defense / Kallysta Castillo/Getty Images

Mr Johnson added: “If and when such a thing were to happen then clearly, with allies, we would study what the options were.”

UN Secretary-General Antonio Guterres urged all Security Council members to exercise restraint and avoid escalation in Syria, but said allegations of chemical weapons use demand an investigation.

In Sydney, Australian Prime Minister Malcolm Turnbull urged Russia to drop its “pretence” that Syria was not behind the chemical attack on Douma and use its influence to force the Assad government to destroy its chemical weapons.

“Russia has used its position as a member of the United Nations Security Council to veto resolutions designed to ensure that this chemical weapons crime is thoroughly investigated and cannot be repeated,” he told a news conference on Sunday.

Biological weapons

Washington described the strike targets as a centre near Damascus for the research, development, production and testing of chemical and biological weapons; a chemical weapons storage site near the city of Homs; and another site near Homs that stored chemical weapons equipment and housed a command post.

The Pentagon said there had been chemical weapons agents at one of the targets, and that the strikes had significantly crippled Syria’s ability to produce such weapons.

There were no immediate reports of casualties.

The United States, Britain and France have all participated in the Syrian conflict for years, arming rebels, bombing Islamic State fighters and deploying troops on the ground to fight that group. But they have refrained from targeting Assad’s government, apart from a volley of US missiles last year.

Inspectors from the global chemical weapons watchdog OPCW were due to try to visit Douma on Saturday to inspect the site of the suspected gas attack. Moscow condemned the Western states for refusing to wait for their findings.

Russia, whose relations with the West have deteriorated to levels of Cold War-era hostility, has denied any gas attack took place in Douma and even accused Britain of staging it to whip up anti-Russian hysteria.

Syria agreed in 2013 to give up its chemical weapons after a nerve gas attack killed hundreds of people in Douma. Damascus is still permitted to have chlorine for civilian use, although its use as a weapon is banned. Allegations of Assad’s chlorine use have been frequent during the war although, unlike nerve agents, chlorine did not produce mass casualties as seen last week.