President Barack Obama, had set a "red line" regarding the use of chemical weapons in Syria and then backed away from military action.
To Trump, the move was emblematic of Obama's weakness. "If President Obama had crossed his stated Red Line In The Sand, the Syrian disaster would have ended long ago!" he tweeted last Sunday as his defense secretary was preparing a military response.
On Friday, Trump struck Syria for the second time with a missile barrage to punish Syrian President Bashar Assad for the use of chemical agents on civilians.
The president's dilemma is that strength and resolve do not necessarily equal a well-thought out Syria strategy. If Assad ignores Friday's relatively modest military strike and continues to use chemical weapons, Trump faces an difficult choice. He can escalate, pulling the U.S. military and his administration into a messy conflict that he recently said he wanted to abandon. Or he can do nothing and risk appearing weak.
"That's not a Syria strategy," said Stephen Biddle, a professor at George Washington University and frequent adviser to the Pentagon. "It's a psychodrama."
The internal contradictions at work in Trump's approach were on full display Friday night when the president addressed the nation.
Even as he promised to strike again if Assad used chemical weapons, Trump made clear that he had no interest in staying in Syria. Last month, he shocked aides when during a speech about infrastructure in Ohio, he announced that U.S. troops would be leaving Syria "very soon." When aides pressed him for a time frame, he initially said he wanted the military to leave in 48 hours, according to a senior administration official, who, like others, spoke on the condition of anonymity to discuss internal deliberations.
Trump's top national security aides in the days that followed talked him into a 4-6 month withdrawal plan.
Assad's chemical weapons attacks - and Trump's outrage over them - clearly have not changed his view of American interests in Syria.
On Friday he called on U.S. allies to do more to stabilize Syria, drive out Assad and ensure Iran does not benefit from the defeat of the Islamic State. He also made clear that America's help would be limited.
"No amount of American blood or treasure can produce lasting peace and security in the Middle East. It is a troubled place," he said. "The United States will be a partner and a friend, but the fate of the region lies in the hands of its own people."
Trump's remarks reflected a view of how America should fight its wars that differs dramatically from many of his generals, who have pressed to keep U.S. troops in places such as Syria, Iraq and Afghanistan indefinitely to rebuild these broken societies and ensure the enemy cannot regenerate.
"His dream would be to have a strong military that protects our homeland," said the administration official. "We'd wall ourselves off and strike at our discretion and then retreat to defending our homeland."
Like Obama before him, Trump has clearly decided that the United States has few interests in Syria and little ability to stop the long civil war, which at the moment the Assad regime, Russia and Iran seem to be winning.
"What we saw last night is that he's worried about the Islamic State and he's worried about chemical weapons," said Mara Karlin, a former Pentagon strategist and professor at Johns Hopkins University. "That's all he cares about."
Obama's narrow view of U.S. interests in Syria left him hesitant to challenge the Assad regime militarily.
Trump is betting that periodic shows of American force - in the form of missiles and fighter jets - can convince Assad and his backers not to use chemical weapons again. He's adopted a similar strategy with regard to North Korea and Iran, where he is wagering that threats of American firepower can produce more pliant behavior.
The approach, Biddle said, reflects Trump's roots as a real estate developer who made risky bets and went bankrupt several times on the way to making billions of dollars. The problem in Syria is that each time Assad uses chemical weapons, Trump has to raise the stakes with a bigger show of force or risk looking feckless.
As the attacks increase in size so too do the odds of a military confrontation with Russia or Iran.
"A fair amount of the time that approach works. The gamble pays off," Biddle said. "But sooner or later it fails and fails catastrophically."
The morning after the missile strikes, Trump seemed convinced his show of strength had worked and would, at least for a while, deter Assad from another chemical weapons strike.
"Could not have had a better result," he tweeted. "Mission Accomplished!"
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)