During the conversation, Mr. Putin repeatedly accused the United States and NATO nations of placing offensive weapons near Russia’s borders, imperiling the country’s security. It is a charge that Russian officials have made repeatedly in recent times, at first puzzling American officials. At first it appeared they might be referring to Javelin anti-tank weapons and other small munitions the U.S. has provided to Ukraine to deter an attack.

But over time, it has become increasingly clear that the Russians are referring to nuclear and non-nuclear “global strike” weapons, including intermediate-range nuclear missiles that were prohibited by a treaty that Moscow violated for several years, and President Trump abandoned. Some U.S. officials say that Mr. Putin’s concern may provide some basis for new negotiations with Russia — especially because there are no current plans to deploy a new generation of such weapons on European soil.