President Trump on Wednesday acknowledged that he is now responsible for handling the ongoing conflict in Syria, but would not say how he intends to address Syrian President Bashar al-Assad's apparent use of a chemical weapon in a deadly attack on civilians this week.

“I now have responsibility,” Trump said at a news conference with King Abdullah II of Jordan in the Rose Garden at the White House on Wednesday. “It crossed a lot of lines for me. When you kill innocent children, innocent babies — babies, little babies — with a chemical gas that is so lethal … that crosses many, many lines, beyond a red line.”

The remarks are the first in which the president described the deep impact that the attack and images of the young victims had on him. He also acknowledged that his position on Assad has changed, though he would not say in what ways.

In the past, Trump has vehemently opposed military engagement in the Syrian conflict.

“I do change and I am flexible,” Trump said. “That attack on children yesterday had a big impact on me. Big impact. It was a horrible, horrible thing.

“It's very, very possible that my attitude toward Syria and Assad has changed very much,” he added.

The president stood by his denunciation of his predecessor, Barack Obama, who he said had left him a “mess” on the global stage. In a statement Tuesday on the chemical attack, Trump blamed Obama's “weakness and irresolution” for Assad's actions.

But asked how he would change the U.S.'s policy, Trump said he would not disclose the details of his strategy.

“One of the things I think you've noticed about me is militarily I don't like to say where I'm going and what I'm doing,” Trump said. “I'm not saying I'm doing anything one way or the other.

“But I'm certainly not going to be telling you,” he added.