 -- President Donald Trump said that the attack in Syria on Tuesday "crossed a lot of lines for me," but he did not specify how he would respond to it.

His comments came during a press conference with Jordan's King Abdullah II that began with Trump's condemning the "heinous actions," which left at least 72 people dead.

Trump was asked if the attack crossed a red line for him, a reference to then-President Barack Obama's 2012 threat that the use of chemical weapons in Syria would be seen as doing so.

"It crossed a lot of lines for me. When you kill innocent children, innocent babies, little babies, with a chemical gas that is so lethal — people were shocked to hear what gas it was — that crosses many, many lines, beyond a red line, many, many lines," he said.

Later, when a reporter noted he seemed reluctant to get involved in the matter, Trump said, "I watched past administrations say we will attack at such and such a day at such and such an hour ... I'm not saying I'm doing anything one way or the other."

He released a statement on Tuesday saying the attack was "a consequence of the past administration's weakness and irresolution."

Today he said, "I think the Obama administration had a responsibility to solve the crisis a long time ago. And when he didn't cross that line in making the threat, I think that set us back a long ways, not only in Syria but in many other parts of the world, because it was a blank threat. I think it was something that was not one of our better days as a country."

Trump added, "I now have responsibility, and I will have that responsibility and carry it very proudly."

He said that he is open to changing his stance on issues and that the attack in Syria was an example of how current events have prompted a shift.

"I like to think of myself as a very flexible person. I don't have to have one specific way, and if the world changes, I go the same way," Trump said. "It's already happened, that my attitude towards Syria and [President Bashar al-]Assad has changed very much."

Later in his remarks, Trump praised Jordan's efforts in the fight against ISIS.

"The Middle East and the entire world is faced with one of its gravest threats in many, many years. Since the earliest days of the campaign against ISIS, Jordan has been a staunch ally and partner, and we thank you for that," he said.

"In King Abdullah, America is blessed with a thoughtful and determined partner. He's a man who has spent years commanding his country's special forces. He really knows what is being a soldier is — that I can tell you. And he knows how to fight," Trump said.