WARSAW — The long convoy from a US armored brigade slid unobtrusively across the German frontier into Poland just before 10 a.m. Thursday.

The convoy is the first installment of what are promised to be several thousand NATO troops to be based across Eastern Europe.

A dozen residents from the southwestern town of Olszyna turned up to watch. “It’s about time,’’ said Jan Siemion, 62, a retired security worker. “Maybe this will stop this guy from the East who has been terrorizing us for decades.’’

After years of yearning for a permanent NATO troop presence along the alliance’s eastern flank — to keep the guy from the East, President Vladimir Putin of Russia, at bay — leaders in Poland and elsewhere were jubilant when a plan to station a rotating contingent of a few thousand multinational troops was approved at the alliance’s summit in Warsaw last summer.

But as those troops are arriving, the situation has radically changed, and the promise of security feels considerably less certain.

President-elect Donald Trump enters office trailing a string of sometimes contradictory statements about NATO and insisting on a new era of chummier relations with Russia’s autocratic leader.

So there is considerable concern in Warsaw and other Eastern European capitals about whether the troops will actually arrive in the numbers promised and whether this desire for friendlier relations with Moscow will undermine the effort.

New York Times