White House walks back suggestion US may respond to additional barrel bombs in Syria Spicer said he can't imagine a "stable and peaceful Syria" with Assad in power.

 -- The White House is walking back a suggestion from press secretary Sean Spicer on Monday that President Donald Trump may take more military action in Syria in response to additional barrel bombings of civilians.

“The answer is, if you gas a baby, if you put a barrel bomb into innocent people, I think you will see a response from this president,” Spicer told reporters this afternoon. “Make no mistake: he will act.”

But a White House aide told ABC News today that "nothing has changed in our posture."

"The president retains the option to act in Syria against the Assad regime whenever it is in the national interest, as was determined following that government's use of chemical weapons against its own citizens," the White House aide said.

Barrel bombs -- an improvised, air-dropped, unguided weapon -- have become a common attack from President Bashar al-Assad's regime, which dropped more than 500 barrel bombs in February, according to human rights groups. President Trump's attack last week was in response to a chemical attack.

Spicer said he can't see Syria become stable without President Assad leaving power, but he stopped short of saying that Assad had committed war crimes by attacking his own people with chemical weapons.

"I can't imagine a stable and peaceful Syria where Bashar al-Assad is in power," Spicer told reporters at his daily briefing on Monday. "We're ensuring that ISIS is contained -- and the proliferation of chemical weapons -- at the same time creating the environment for a change in leadership."

Still, he stopped short of labeling Assad a war criminal during today's briefing. "I think that there is a court that decides those things," Spicer told reporters. "That would be something for a court to decide."

President Trump did accuse Syria of violating the chemical weapons ban during his statement after the bombing. "There can be no dispute that Syria used banned chemical weapons, violated its obligations under the chemical weapons convention and ignored the urging of the U.N. Security Council," he said.

Trump ordered a missile attack on an airfield in Syria last Thursday after at least 87 civilians, including 31 children, were killed in the chemical attack on April 4.

The Syrian government has denied carrying out the attack.