President Biden and his nationwide safety staff have contended since he took workplace that each one the simple, tempting comparisons between this period and the Cold War are deceptive, an enormous oversimplification of a fancy geopolitical second.

The variations are, certainly, stark: The United States by no means had the form of technological and monetary interdependence with its Cold War adversary, the Soviet Union, that so complicates the more and more bitter and harmful downward spiral within the relationship with China.

And Mr. Biden’s advisers typically argue that Russia just isn’t the Soviet Union. Yes, it has nuclear weapons, they are saying, however its typical navy capability has now been severely degraded in Ukraine.

And in Soviet occasions, the United States felt compelled to struggle an ideological battle world wide. In the brand new period, it’s combating China’s efforts to make use of its financial and technological energy to unfold its affect.

Nonetheless, the echoes of the Cold War are rising louder. Mr. Biden himself added to the din this week. In Vilnius, Lithuania, on Wednesday night time, addressing a crowd that was waving American, Lithuanian and Ukrainian flags, he repeatedly invoked the battle of the Baltic nations to free themselves from a collapsing Soviet Union, and informed Vladimir V. Putin that the United States and its allies would defend Ukraine, and with it different weak components of Europe, “as long as it takes.”

Mr. Biden by no means fairly mentioned explicitly that the United States should once more “bear the burden of a long, twilight struggle” — President Kennedy’s well-known description of the Cold War in his 1961 inaugural handle, because it entered its most harmful part. But Mr. Biden’s message was basically the identical.

“Our commitment to Ukraine will not weaken,” he mentioned. “We will stand for liberty and freedom today, tomorrow, and for as long as it takes.”