Mr. Voinovich cited a Tuesday article in The Wall Street Journal that said Russia had moved smaller, tactical nuclear weapons to its western border as recently as this spring. Mr. Voinovich said he had talked with Eastern European officials, who told him that ratification of New START, which applies to strategic nuclear weapons, was a necessary first step toward addressing tactical nuclear weapons and other regional security concerns in subsequent negotiations.

Mr. McCain said he was “a little disturbed at the news this morning that tactical nuclear weapons have been moved closer to Europe by the Russians,” saying it showed “the need to have verification.” Mr. Obama has vowed to begin negotiations on a binding, verifiable treaty covering tactical nuclear weapons and other issues as soon as New START is ratified.