Britain and Australia offered strong backing to the US missile strike on Syria, ordered in response to a deadly chemical attack in the country this week, but Russia described it as "thoughtless" and called for an emergency meeting of the UN Security Council in response.
Here’s how world leaders have reacted to the US attack.
Britain offered unqualified support for the US strike. “The UK government fully supports the US action which we believe was an appropriate response to the barbaric chemical weapons attack launched by the Syrian regime and is intended to deter further attacks,” a spokesman for the government said.
Defence secretary Michael Fallon said his US counterpart James Mattis asked for Britain's view on whether the Assad regime was responsible for the chemical attack in Idlib province this week before launching the strikes.
"The American defence secretary Jim Mattis consulted me early yesterday evening about our assessment of the regime's culpability for the chemical weapons attack and we reviewed the need to understand and to deal with any likely Russian reactions to the attack," he told BBC television.
“He was then reviewing the different options to put before the president; he then called me later on to advise us of the president’s decision and to give us notice of the attack and our prime minister was kept informed throughout.”
President Vladimir Putin condemned cruise missiles strike on as illegal, warning the move would further damage already battered US-Russia relations which Moscow had hoped Donald Trump would revive.
“President Putin views the US strikes on Syria as aggression against a sovereign state in violation of the norms of international law and on a made-up up pretext,” said a Kremlin statement. “This step by Washington will inflict major damage on US-Russia ties.”
Mr Putin, a staunch ally of Syrian president Bashar al-Assad, was holding a meeting of Russia’s security council to discuss the strike on Friday afternoon, and the Russian foreign ministry called for an emergency meeting of the UN Security Council.
A foreign ministry statement said Moscow was suspending a Syrian air safety agreement with the United States, originally drawn up to ensure that the two countries' planes did not collide.
“It’s clear to any specialist that the decision to launch a strike was taken in Washington before the events in Idlib [the province where the gas poisoning took place] which were simply used as a pretext for a show of force,” the ministry said.
Dmitry Peskov, Mr Putin's spokesman, told reporters the US strikes had been conducted to help rebel groups fighting Mr Assad. Russia would keep military channels of communication open with Washington, but would not exchange any information through them, he added.
When asked whether Russia had deactivated its own anti-missile defence systems in Syria before the missile strike, Mr Peskov declined to comment.
The Russian defence ministry mocked the effectiveness of the US strike, saying only 23 missiles had found their targets. It was unclear where another 36 had landed, it said, promising Syrian air defences would now be beefed up.
A Russian frigate armed with Kalibr cruise missiles sailed through the Bosphorus en route to the eastern Mediterranean in the early hours of Friday morning, according to pictures taken by Turkish bloggers for their online Bosphorus Naval News project. It was unclear if that was related to the US strikes.
Foreign minister Sergei Lavrov said there were no reports of any Russians being hurt in the attack. He said he hoped US-Russia ties would not be irreparably hurt as a result. Rex Tillerson is due to make his first visit to Moscow next week as US secretary of state, an eagerly awaited event in Russia where politicians have been anxious to try to use the change of administration to reboot relations.
Prime minister Malcolm Turnbull described the missile strike as a "proportionate and calibrated response" to the use of chemical weapons. The US action sent "a vitally important message" that the world would not tolerate the use of chemical weapons, he said.
"The retribution has been proportionate and it has been swift," he told reporters in Sydney. "We support the United States in that swift action."
Mr Turnbull said the military action was not designed to overthrow the Assad regime, though the reported use of chemical weapons did “raise questions as to whether there can be any role for Mr Assad in any solution or settlement”.
He called on Russia to do more to ensure peace in Syria.
Israel welcomed the missile strike and said it was informed of the action shortly before the missiles were launched.
In a statement released a few hours after the strike, prime minister Binyamin Netanyahu praised the American move. "In both words and action, President Trump sent a strong and clear message today that the use and spread of chemical weapons will not be tolerated," he saidt.
"Israel fully supports President Trump's decision and hopes that this message of resolve in the face of the Assad regime's horrific actions will resonate not only in Damascus, but in Tehran, Pyongyang and elsewhere."
Israel's president, Reuven Rivlin saod the US strike was a "fitting and appropriate response" to the use of chemical weapons in Syria.
Opposition leader Yitzhak Herzog also welcomed the US action, saying it came at the "right time and in the right place".
Iran denounced the strike, the Students News Agency Isna quoted a foreign ministry spokesman as saying. "Iran strongly condemns any such unilateral strikes. Such measures will strengthen terrorists in Syria ... and will complicate the situation in Syria and the region," Isna quoted Bahram Qasemi as saying.
Beijing urged all parties in Syria to try to find a political settlement in the six-year-old war after the US military strike, which came as China’s president was in talks with Donald Trump. Foreign ministry spokeswoman Hua Chunying said China hoped that relevant parties would “stay calm, exercise restraint and avoid doing anything that might raise tensions”.
“The latest developments in Syria again speak to the urgent need for a political settlement to resolve the Syria issue,” Ms Hua told reporters at a regular briefing. “We call on all relevant parties to resolutely stick to promoting a political settlement and not abandon efforts to find a political settlement.”
Saudi Arabia said it "fully supports" US strikes on military targets in Syria, saying it was a "courageous decision" by Donald Trump in response to the use of chemical weapons against civilians.
“A responsible source at the foreign ministry expressed the Kingdom of Saudi Arabia’s full support for the American military operations on military targets in Syria, which came as a response to the Syrian regime‘s use of chemical weapons against innocent civilians,” a statement carried by state news agency SPA said.
Germany & France
German chancellor Angela Merkel and French president Francois Hollande laid the blame for the US military attack on Syria at the door of Bashar al-Assad. Ms Merkel and Mr Hollande held a phone call on Friday morning to discuss the US action, said to a statement distributed by the Federal Chancellery in Berlin and the Élysee Palace in Paris.
The German and French leaders pointed to the killing of scores of civilians with poison gas this week in a rebel-held enclave in the northwestern Syrian province of Idlib, an assault for which the US and its allies have blamed Mr Assad, backing Donald Trump’s justification that the deployment of chemical weapons was “an affront to humanity”.
“President Assad alone bears responsibility for this development,” Ms Merkel and Mr Hollande said. “His repeated use of chemical weapons and his crimes against his own population had to be sanctioned.”
French foreign minister Jean-Marc Ayrault said France was informed of the missile strike in advance.
"I was told by [US secretary of state] Rex Tillerson during the night," Mr Ayrault said in the Mauritanian capital Nouakchott, where he is on a diplomatic visit. "Use of chemical weapons is appalling and should be punished because it is a war crime."
Italy gave its support to the US action, saying it was a suitable response to Syrian aggression and a deterrent against the use of chemical weapons by its leader Bashar al-Assad.
“Italy understands the reasons for the US military action,” foreign minister Angelino Alfano said in a statement. The strike was “a commensurate response ... and a signal of deterrence against the risks of further use of chemical weapons by Assad.”
Italy currently holds the rotating presidency of the Group of Seven industrialised nations.
The country’s two largest opposition parties, the anti-establishment 5-Star Movement and the anti-immigrant Northern League, both condemned the US strike.
Deputy prime minister Numan Kurtulmus offered support for the strikes and said the international community should sustain its stance against the "barbarity" of the Syrian government.
In an interview with Turkish broadcaster Fox TV, Mr Kurtulmus said that the government of Mr Assad must be fully punished in the international arena and that the peace process in Syria needed to be accelerated.
European Commission president Jean Claude Juncker said the use of chemical weapons in Syria “must be answered”, after the US missile strike on an airbase in Syria that Washington said was used for such attacks.
“The US has informed the EU that these strikes were limited and seek to deter further chemical weapons atrocities,” Mr Juncker said in a statement. He “understood” efforts to deter further chemical attacks. “There is a clear distinction between air strikes on military targets and the use of chemical weapons against civilians.”
Indonesia said it strongly condemned the use of chemical weapons in Syria. "At the same time, Indonesia is concerned with unilateral actions by any parties, including the use of Tomahawk missiles, in responding to the chemical weapon attack tragedy in Syria," foreign ministry spokesman Armanatha Nasir said in a text message.
“Military actions, undertaken without prior authorisation of the UN Security Council, are not in line with international legal principles in the peaceful settlement of disputes, as stipulated in the UN Charter.”