Iran’s President Hassan Rouhani has said “terrorists are celebrating” US strikes on a Syrian airbase.
His comments echo the response from Russia, which like Iran is allied to Syria, and from Syria itself.
At least six people are reported to have been killed in the missile strikes in the early hours of Friday.
The strikes followed Wednesday’s suspected chemical attack on the rebel-held town of Khan Sheikhoun, in which 89 people are reported to have died.
Syria denies using nerve gas, saying instead that its missiles struck a storage facility where rebel forces were keeping chemical weapons.
The UK’s Foreign Secretary Boris Johnson has since called off a visit to Moscow, saying the situation had changed “fundamentally” and he would work with the US in pursuit of a ceasefire.
In the Syrian capital Damascus and around the world, people protested against the air strikes, insisting there should be no US war against Syria.
In a speech broadcast on state television, Mr Rouhani said: “The man who is now in office in America claimed that he wanted to fight terrorism. But today, all the terrorists in Syria are celebrating this US attack.
“Why did you help terrorist groups and support them in your first move?”
Iran has used the term “terrorist groups” to refer to rebels, many backed by the US, who are fighting against Syria’s President Bashar al-Assad.
But he backed calls for an independent inquiry into the suspected chemical weapons attack.
The US provides arms, training and military assistance to what it calls “moderate” Syrian rebel groups. It has led a coalition carrying out air strikes against jihadist groups in Syria since 2014 but this is the first time it has targeted government forces.
What happened in the US air strike?
Two US Navy destroyers in the Mediterranean Sea fired 59 Tomahawk cruise missiles at Shayrat air base in western Homs province at about 04:40 Syrian time (01:40 GMT) on Friday.
They targeted aircraft, aircraft shelters, storage areas, ammunition supply bunkers and air defence systems at the Syrian government-controlled facility, according to the Pentagon.
The Pentagon said the base was used to store chemical weapons and that “every precaution” had been taken to avoid casualties. The Russian military was informed beforehand, a US military spokesman said.
Syrian state media said as many as nine civilians had been killed in the strike, four of them children. The BBC is unable to confirm this information.
What have other Syria allies said?
Like Iran, Russia accused the US of encouraging “terrorists” with its air strike.
Russia’s deputy ambassador to the UN, Vladimir Safronkov, was quoted as saying: “It’s not difficult to imagine how much the spirits of these terrorists been raised.”
US Secretary of State Rex Tillerson said Russia’s response indicated “continued support for a regime that carries out these type of horrendous attacks on their own people”.
North Korea, meanwhile, called Friday’s strike “an unforgivable act of aggression” which showed its own decision to develop nuclear weapons was “the right choice a million times over”.
How does this change things between the US and Russia?
The decision to send cruise missiles against the Syrian government, which counts Russia as its most powerful ally, is a dramatic U-turn for the Trump administration.
Just last week Mr Tillerson said President Assad’s future would be “decided by the Syrian people”.
But the images coming out of Khan Sheikhoun appear to have changed all that.
“Even beautiful babies were cruelly murdered in this very barbaric attack,” Mr Trump said.
“It is in the vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons.”