Palm Beach: President Donald Trump first saw the photos Tuesday morning.
The images were ghastly. Men and women gasping for breath. Small children foaming at the mouth and in agony. The lifeless bodies of babies sprawled on the ground.

This was the aftermath of a chemical attack ordered by Syrian President Bashar Assad, who the U.S. would soon conclude had unleashed sarin gas, a brutal nerve toxin, on his own people.

The president peppered his advisers with questions, according to national security adviser H.R. McMaster, who later said Trump was immediately focused on getting to the bottom of "who was responsible." By the end of the briefing, the president had dispatched his team to draw up options for a response.

The leap to considering intervention was remarkable. In 2013, Trump had argued against military intervention in Syria when it was President Barack Obama's decision to make. He had hardly portrayed himself as a humanitarian crusader on the campaign, when he adopted the slogan "America First."

Just last week, the White House declared itself resigned to the status quo of a Syria led by Assad. It was "a political reality that we have to accept," White House spokesman Sean Spicer had said.

But as Trump spent Tuesday in meetings about the nation's business climate and his infrastructure plan, the images from Syria weighed on him, his aides said. He was disturbed by images of "babies," some the ages of his grandchildren.

Tuesday evening the National Security Council's Deputies Committee briefed Trump with options, a meeting that set in motion a new president's startling transformation from resigned to resolved to act.

He revealed his horror, saying the images "of innocent children, innocent babies" killed by poison gas were causing him to rethink his approach on Syria.

"It's very, very possible, and I will tell you it has already happened, that my attitude toward Syria and Assad has changed very much," Trump said. The attack "crossed a lot of lines for me." "I now have responsibility," Trump said, "and I will have that responsibility and carry it very proudly."

Later that afternoon, Trump convened a meeting his top national security advisers to review three options ranging in levels of risk and scope. The details on each are not clear. But a U.S. official with knowledge of the proposals said one plan would have targeted a number of chemical weapons sites, a move that would have directly diminished Assad's ability to carry out future attacks.

But the military was concerned that if an attack resulted in chemical agents being dispersed, the U.S. could be blamed for any sickness or death, said the official, who was not authorized to discuss secret military plans.

Another option was the firing of Tomahawk missiles at an air field, an attack viewed as sending a signal to Assad. It was recommended by the Pentagon, the official said, and the one Trump would ultimately choose. But not yet. Trump agreed to meet with the team again Thursday.

Trump and a number of aides were flying to the president's Mar-a-Lago resort for a summit with Chinese President Xi Jinping. The much-anticipated meeting, unbeknownst to the reporters onboard, would soon be overshadowed.

Elsewhere on that same aircraft, Trump convened his national security team and consulted with others, including Vice President Mike Pence, over secure video conference to discuss the options again. The president was close to a decision.

After the meeting he stopped by the press cabin to talk to reporters. As a scene from the "Star Wars" movie "Rogue One" played on the TV over his shoulder, he called the chemical attack "a disgrace to humanity" and hinted that "something should happen," but offered no further details.

Shortly after landing in Florida, Trump and the team huddled again, this time in a freshly constructed secure room at Trump's palatial oceanside estate. Trump then gave approval to launch nearly 60 Tomahawk cruise missiles at the airfield believed to be the source of the chemical attacks