US Treasury Secretary Steve Mnuchin has told reporters that he plans to announce additional economic sanctions aimed at Syria in the near future, part of the US response to a poison gas attack that Western countries say was carried out by the government of Syrian President Bashar al-Assad.
"We expect that those (sanctions) will continue to have an important effect on preventing people from doing business with them," Mnuchin said on Friday. "These sanctions are very important and we will use them the maximum effect."
Meanwhile, US Ambassador Nikki Haley has delivered a warning at an emergency session of the UN Security Council.
"The United States took a very measured step last night," Haley told the council. "We are prepared to do more, but we hope it will not be necessary."
Launched in retaliation for a chemical attack blamed on President Bashar al-Assad's government, the missile strike marked the first direct US assault on his regime.
Haley said the strike destroyed an air field from which Washington believes Damascus launched the attack on rebel-held Khan Sheikhun, where 86 people including 27 children died this week.
"We were fully justified in doing so," she said.
Satellite image released of Syrian air-strike target
The United States fired 59 Tomahawk cruise missiles from warships in the Mediterranean at the Shayrat airfield near Homs in central Syria.
But the Syrian Observatory for Human Rights said the central Syrian air base was partially back in service by Friday, and that warplanes took off from it hours after the US raid and carried out bombing raids nearby.
Assad's office called the strike "foolish and irresponsible" and Moscow announced a series of retaliatory steps including plans to strengthen Syrian air defenses.
"The United States will no longer wait for Assad to use chemical weapons without any consequences," Haley said. "Those days are over."
Russia accuses US
The United States did not seek Security Council authorization for the military action that followed days of global outrage at images of dead children from the suspected sarin gas attack.
It was Trump's biggest military decision since taking office and marked a dramatic escalation in American involvement in Syria's protracted war.
"The United States attacked the territory of sovereign Syria," Russian Deputy Ambassador Vladimir Safronkov told the council, denouncing a "flagrant violation of international law and an act of aggression."
Syrian army spokesman on US attack
"What America did is nothing but foolish and irresponsible behavior, which only reveals its short-sightedness and political and military blindness to reality," Assad's office said.
Damascus has denied using chemical weapons in Khan Sheikhun.
In Washington, a senior US official said Syria may have had help carrying out the alleged chemical attack, but stopped short of accusing Russia of complicity.
"We know the Russians have chemical expertise," said the official, who spoke on condition of anonymity. "We are carefully assessing any information that would implicate the Russians knew or assisted with this capability."
A new phase
While threatening further strikes, the US ambassador also said it was time to press on with diplomatic efforts to achieve a political solution to end the war.
"Now we must move to a new phase: a drive toward a political solution to this horrific conflict."
UN Secretary General Antonio Guterres urged restraint and a renewed push for peace in Syria, saying "there is no other way to solve the conflict than through a political solution."
Experts analyse Syrian attack aftermath
Britain, Canada, France, Germany, Israel, Japan, Saudi Arabia and Turkey all supported Washington, with Ankara also calling for a no-fly zone in Syria.
But with US Secretary of State Rex Tillerson due in Moscow next week, the Kremlin warned the US military action would inflict "considerable damage" on US-Russia ties.
It immediately suspended a deal with the United States aimed at avoiding clashes in Syrian airspace, though the foreign ministry did not scrap Tillerson's visit.
'Low' impact
Trump announced the strike in a brief televised address.
"Tonight I call on all civilized nations to join us in seeking to end this slaughter and bloodshed in Syria and also to end terrorism of all kinds and all types," he said.
Fired from the USS Porter and the USS Ross, the cruise missiles targeted radars, aircraft, air defense systems and other logistical components.
Australian government reacts to US-Syria airstrike
The Syrian Observatory said the US strike on the base killed eight Syrian military staff, including an army doctor. Syria's army had earlier said six people were killed in the strike, without specifying if they were military personnel or civilians.
Russia's military said the strike had an "extremely low" military impact, with fewer than half the missiles reaching the base.
It destroyed six planes under repair and several buildings, including a storage depot and radio station, it said.
Pentagon footage of Tomahawk missile launch
US officials said Russia's military in Syria was informed of the strike beforehand in order to avoid casualties.
A Syrian military source said its armed forces had also received advance warning.
Russia has stood by Damascus despite the global uproar, insisting the chemical weapons that caused the deaths in Khan Sheikhun had been stockpiled by "terrorists" and possibly released by a conventional strike.
Syrians welcome US strike
In the blighted town itself, residents mourning their dead welcomed the US strike as a way to pressure Damascus.
"God willing, these strikes will be a clear warning to Bashar al-Assad, to tell him: Bashar, enough killing and injustice against these people," said Abu Ali, a man in his 40s.
Opposition and rebel fighters, who have for years urged more direct US military action in support of their uprising, hailed the strike and called for more.
The National Coalition, the main opposition grouping, urged Washington to "neutralize" the regime's air power while the Free Syrian Army and other rebel factions called for more strikes to "prevent the regime from using its airports and internationally-banned weapons against Syrians".
Turkish President Recep Tayyip Erdogan, a longtime foe of Assad, also called for more "steps for a serious result to protect the oppressed Syrian people."
The White House has painted its decision as limited to deterring the use of chemical weapons, and not part of a broader military campaign.
Trump had previously indicated no willingness to engage further in Syria's war, beyond stepping up efforts to battle Islamic State jihadists, who have been targeted by US-led air strikes in Syria and Iraq since mid-2014.
Since Khan Sheikhun the United States has changed tack, with Trump warning that the "barbaric" attack required a response, and Tillerson calling for "a political process that would lead to Assad leaving."
