As President Trump fired off a series of social media posts criticizing Germany this week, including a threat to pull some American troops from the country, German leaders showed no public signs that they believed the president was serious.

That now appears to have been a miscalculation — one of several that German leaders have made in the course of Mr. Trump’s war against Iran.

Pentagon officials said on Friday that they planned to relocate 5,000 troops from Germany to the United States and around the world within the next year. German officials offered no immediate public reaction.

The Americans privately made clear the move was meant to punish Germany, for not helping more with the war effort, as Mr. Trump has demanded, and for criticizing Mr. Trump’s strategy from the highest levels.

Until that announcement, the consensus view in German politics appeared to be that Mr. Trump was most likely bluffing with his redeployment threats. He had tried, and failed, to remove some of America’s 35,000 troops from Germany at the end of his first term in office. He would need congressional approval to move troops from Europe now.

In early March, when Friedrich Merz, the German chancellor, visited Mr. Trump in Washington, Mr. Merz said the president had taken any threat of troop reductions off the table.

“President Trump has also assured me not just today, but once again, that the United States will maintain its military presence in Germany,” Mr. Merz told reporters in a German-language news conference near the Capitol, shortly after meeting Mr. Trump.

German leaders were also confident that the Trump administration needed its military presence in Germany as much, or more, than the Germans did. Unlike some other European allies, Germany had allowed America to help launch attacks on Iran from bases inside Germany’s borders. It has continued to allow injured Americans to be treated in a major American hospital on German soil that has for decades hosted Americans injured in wars including in Afghanistan and Iraq.

Germany’s quiet nonchalance about the possibility of a troop withdrawal was reflected again this week.

Mr. Merz offered no public apologies or retreat from his seemingly off-the-cuff comments on Monday that criticized Mr. Trump’s war strategy in harsh terms. He had told German high-school students that the United States had “no strategy” to end the war and that Iran’s negotiators had “humiliated” the entire American nation.

On Thursday, Mr. Merz, who invested heavily in building a rapport with Mr. Trump over the last year, told German soldiers in the city of Munster that “we maintain close and trusting contact with our partners, including and especially in Washington.” He stressed the relationship with Washington was one of mutual respect and fair sharing of security burdens.

“This trans-Atlantic partnership is especially important to us, and to me personally,” he said, but did not offer an apology for the comments that had ignited the row with Mr. Trump.

Then Mr. Merz’s vice-chancellor, Lars Klingbeil, raised tensions further on Friday, clapping back at another critical social media post from Mr. Trump.

In a May Day speech, Mr. Klingbeil defended Mr. Merz from the president’s broadsides. “We really don’t need any advice from Donald Trump right now,” Mr. Klingbeil said. “He should see the mess he’s made” with the war, he added.

Mr. Klingbeil leads the center-left Social Democrats, the junior partner in a governing coalition led by Mr. Merz’s center-right Christian Democrats. He has been more critical of Mr. Trump in the past than Mr. Merz. He also had been traveling with Mr. Merz in Munster, and has been in close consultation with him over a host of domestic issues recently.

Mr. Trump has consistently surprised German leaders with his conduct in the war. After Mr. Merz met with the president in the Oval Office and over lunch at the White House in March, some officials came away convinced that the conflict would not last long because Mr. Trump was already expressing concerns over the economic effects of war-related energy price spikes.

Instead, Mr. Trump persisted with attacks even after gasoline and natural gas prices rose sharply from Iran’s closure of the Strait of Hormuz.

German officials also believed they had found a sort of compromise with the president over his demands that Europe send military assets to secure the strait and make it safe for shipping again.

Mr. Merz said repeatedly that Germany would join such a security effort, including by sending minesweepers, but only on two conditions: Germans wanted a permanent cease-fire, as opposed to the temporary one currently in place. And to comply with the German constitution, they wanted the effort to have the blessing of an international body, like the United Nations or the European Union.

That appears not to have been enough for Mr. Trump. On Friday, a Pentagon official did not just cite Mr. Merz’s comments as a reason to pull back troops. The official also cited Germany’s failure to contribute to the Iran war effort itself.

Julian E. Barnes and Helene Cooper contributed from Washington.