It was President Trump's idea to issue a statement this week warning Syrian President Bashar Assad against using chemical weapons on its people, White House deputy press secretary Sarah Sanders said on Wednesday.

"The president proposed issuing a statement that warned the regime of consequences," Sanders told reporters during Wednesday's briefing, as she provided a timeline of how the statement originated.

On Monday evening, the White House released a statement saying it had "identified potential preparations for another chemical weapons attack by the Assad regime" and warned Assad that he and "his military will pay a heavy price" if that occurs.

Sanders pushed back against reports that the statement was hastily released without relevant officials in the government having participated in its drafting.

"There were a lot of stories about the process not working or relevant agencies and people being out of the loop," Sanders said. "Those are simply false."

Sanders said that at a regularly scheduled meeting, Trump was presented with information that indicated the Assad regime was preparing another chemical weapons attack. The president proposed releasing such a statement himself, she said.

She said senior administration officials, including national security adviser H.R. McMaster, Director of National Intelligence Dan Coats and CIA Director Mike Pompeo were present when the statement was initially proposed. Sanders also said Secretary of State Rex Tillerson and Defense Secretary Jim Mattis were consulted in person later that day.

"The military chain command was also fully aware of the statement as it was being prepared and later released," she said.

Sanders said Tillerson also spoke to his Russian counterpart about the statement and the White House staff secretaries reviewed the statement and coordinated messaging and solicited comments from relevant departments and agencies.

"By the time the statement was issued, every relevant department and agency had ample opportunity to provide feedback," she said.

While traveling in Europe, Mattis said the warning was having the desired effect on Damascus.

"They didn't do it," Mattis told reporters on his plane while flying from Germany to Belgium. "It appears they took the warning seriously.