Republicans have hoped that Trump's foreign policy might evolve from the "America first" approach that suggested he wasn't interested in being a global leader. And, they have strongly urged the president to stop coddling Russian strongman Vladimir Putin.
Trump's decision to hit Syria with missile strikes in retaliation for using chemical weapons, and his administration's stern warning to Damascus' key ally, Russia, that such behavior wouldn't be tolerated, left senior Republicans optimistic that the president is finally changing course.
"This action reminded me of [former President] George W. Bush," Senate Majority Leader Mitch McConnell, R-Ky., said in an interview with the Washington Examiner. "It was well-planned, well-executed — sent multiple messages."
McConnell said the strike put Syrian dictator Bashar Assad on notice that murdering civilians is unacceptable. The majority leader said it also signaled to U.S. adversaries and allies alike that "America is back, and playing a leadership role."
Republicans chafed under the foreign policy of former President Barack Obama. They criticized the Democrat for diminishing U.S. influence, charging that he appeased adversaries and neglected allies.
Similar to Obama, Trump argued that the U.S. was over-extended abroad and needed to refocus inward. The Republican appeared to go further, however.
Trump indicated that he was prepared to discard decades of bipartisan foreign policy consensus, formulated in the aftermath of World War II, and in particular embraced by the GOP since Ronald Reagan's presidency, that America had a unique role to play.
That's why Trump's action against Syria was so reassuring to Republicans. It symbolized to them that Trump was rejecting his isolationist tendencies, and embracing the hawkish foreign policy that has dominated his party for nearly four decades.
"I was proud of him," said Sen. Lindsey Graham, R-S.C., a hawk who has been sharply critical of Trump's foreign policy. "He called me last night, and he said: 'Well, I bet you're happy.' I said: 'No, I'm proud. I'm proud that you did something that needed to be done.'"
Even a few Democrats praised Trump, however sparingly. While making clear that they wanted the president to communicate, more specifically, his military and diplomatic strategy for Syria, they were generally pleased to see him embrace a traditional foreign policy.
"I support this action by President Trump," said Sen. Chris Coons, D-Del., who serves on the Foreign Relations Committee. "Assad's murderous campaign against his own people has gone on far too long."
Trump's flirtation with Putin has rankled Democrats and Republicans. But the matter has been particularly distressing for a GOP proud of its foreign policy heritage as the party that won the Cold War and presided over the demise of the Soviet Union.
So despite their acceptance of the president's various political eccentricities, they have resisted him on Russia. Republicans have begged Trump to treat Moscow as an adversary and recognize its bad behavior, from repressing democracy at home to invading neighbors, not to mention undermining U.S. interests.
The Trump administration additionally delivered a stern message to Russia that complicity with Assad's use of chemical weapons was unacceptable. All of that has deepened the Republicans' confidence that the president's infatuation with Putin might be over.
"For a lot of people, it will probably put to rest all this discussion about, oh, he and Putin are holding hands together," said Sen. James Risch, R-Idaho, a pointed Russia hawk who serves on the intelligence committee. "If that was the case on Wednesday, it wasn't the case by midnight on Thursday."