President Donald Trump’s sudden foreign-policy pivot, from “America First” to international engagement through military action and re-embracing NATO, may have reduced fears about him within the Republican Party establishment.

But many voters may now see him flip-flopping from his inauguration pledge to reform immigration and health care, by intervening in the Syrian civil war and backtracking on declaring NATO “obsolete.”

Coupled with Trump’s removal of chief strategist Stephen Bannon from his National Security Council (and possibly a rebuff to Mr. Bannon’s economic nationalism ideology), GOP regulars have a basis to see the new president as less hostile to them.

Sens. John McCain and Lindsey Graham have been quick to applaud Mr. Trump’s measured naval missile attack in response to the Syrian regime’s use of chemical weapons against Syrian rebels and allies.

Mr. Trump defended his launch order mostly in humanitarian terms, suggesting he was acting through a mood change that has often marked his impulsive decision-making. But the attack also strengthened his case for early liquidation of the Islamic State, the declared target of the swift retaliation against chemical weapons use.

The main events of recent days have also spotlighted a hardened Trump posture regarding his relations toward Russia and President Vladimir Putin, which previously had taken on the aspect of a mutual admiration society.

His dispatch of Secretary of State Rex Tillerson to Moscow for meetings with Foreign Minister Sergey Lavrov and Mr. Putin signaled a return to formal diplomacy in what Mr. Tillerson acknowledged was a low point in U.S.-Russian affairs.

As for missile attack itself, its limited and targeted implementation underscored the determination of Secretary of Defense James Mattis and National Security Council Adviser H.R. McMaster to avoid undue peril to the diplomatic efforts involved.

Unfortunately, a subsequent U.S air attack on a suspected Islamic State facility in Syria went awry Thursday when friendly fire was mistakenly delivered, killing at least 18 members of allied Syrian Democratic Forces in what the Pentagon said was a case of erroneous targeting.

Such occurrences are not uncommon in warfare, but they are particularly unwelcome in a new American administration whose president is known for unpredictability, and for often functioning without a reliable grasp of the facts at hand.

But some of President Trump’s recent turnabouts have been reassuring to Republican doubters who see them as evidence that he is settling into the reality of his presidency, and feeling comfortable enough to acknowledge changes of mind. He recently self-identified himself as “flexible” on various issues.

On his earlier defining of NATO as obsolete, Mr. Trump had recently credited member-states with responding positively to his criticism that they were not meeting their pledge to spend 2 percent of their gross national product on defense spending.

He similarly said after his Florida meeting with Chinese President Xi Jinping that he no longer considered China “a currency manipulator,” nor was he still opposed to the Export-Import Bank, and he might well reappoint Janet Yellen as chair of the Federal Reserve.

Mr. Trump’s embattled White House press secretary, Sean Spicer, last week argued that the president had brought some of his critics around, rather than flip-flopping.

“If you look at what’s happened,” Mr. Spicer said, “it’s those entities or individuals in some cases or issues evolving toward the president’s’ position, where he wanted NATO in particular to evolve to, and it’s moving exactly in the direction that he said it was in terms of its goals of increasing the amount of participation from other member countries.”

Some of the Republicans who opposed Mr. Trump in the 2016 GOP presidential primaries have taken heart in the emergence of his son-in-law, Jared Kushner, as his principal policy adviser, and as a counter to Mr. Bannon in the Trump inner circle. President Trump’s comment that Mr. Bannon “works for me” came off as an intentional put-down by the president, known as unwilling to have a latecomer to his operation seen as a rival power-center to himself.

In all, the events of the last week appear to have modestly enhanced his presidential image, if only by his acting somewhat more responsible and aware of what it takes to exert real national leadership.

Jules Witcover is a syndicated columnist and former longtime writer for The Baltimore Sun. His latest book is "The American Vice Presidency: From Irrelevance to Power" (Smithsonian Books). His email is juleswitcover@comcast.net.