Another letter, dated Tuesday and sent by the American College of National Security Leaders, a group of former high-level military officers, said: “The INF Treaty is a bedrock to our current arms control regime and serves rather than hampers American interests.”

There was no immediate comment from the Trump administration on the letters.

The treaty’s fate may come up this weekend if Mr. Trump sees President Vladimir V. Putin of Russia during a memorial event in France celebrating the centennial of the end of World War I. But there have been conflicting accounts from the White House and the Kremlin on whether the two will even meet.

Mr. Putin and his subordinates have warned of a new arms race should Mr. Trump make good on his pledge to renounce the accord. It would be the first time Mr. Trump has scrapped an arms-control treaty, American officials have said.

Many European leaders also have objected to Mr. Trump’s plan.

Mr. Trump and his hard-line aides, particularly John R. Bolton, the national security adviser, have long disparaged the treaty, asserting that Russia has cheated on its terms and that it should include China, which is not a signatory.

The treaty ended a crisis of the 1980s that had come to be seen as a hair-trigger for a nuclear war. The Soviet Union had deployed a missile in Europe called the SS-20, capable of carrying three nuclear warheads. The United States had deployed cruise and Pershing II missiles. All had the capability of reaching targets in as little as 10 minutes.