The senior U.S. diplomat for arms control, John Bolton, is visiting Moscow this week to urge Russia to join an international alliance of countries working to halt the trade in weapons of mass destruction.

President Bush announced the so-called Proliferation Security Initiative last May. According to U.S. officials, it includes as many as 16 countries in the fight to halt the spread of weapons of mass destruction.

Russia is not a participating member of the group, although President Vladimir Putin has said publicly that Russia must do more to combat the spread of such weapons.

During his visit to Moscow, Undersecretary of State for Arms Control and International Security John Bolton is expected to urge Russian officials to join the Proliferation Security Initiative.

But Russia has little to gain in a practical sense from agreeing to such cooperation, says Danil Kobyakov, a senior researcher on nuclear issues with the non-governmental PIR Center for Political Studies in Moscow.

"Basically, all the implementation will be carried out by the American side," he said. "So if Russia can gain any concessions ... then that would probably be an advantage."

He said the best the two sides are likely to accomplish during Mr. Bolton's visit is to clarify terms under which Russia would participate in the non-proliferation initiative.

He said he expects some progress in the U.S. cooperation with Russia in dealing with North Korea over its nuclear program. Russia is part of a group of countries, which includes the United States, Japan, South Korea and China, which are holding talks with Pyongyang on ending the nuclear program.

The question now, Mr. Kobyakov said, is whether North Korea will be ready to cooperate. "Here, I think much depends on the cooperation between the United States and Russia, as well as China and other countries. But definitely this question will be on the agenda," he said.

Mr. Kobyakov said another issue on top of Mr. Bolton's agenda will be convincing Moscow to continue withholding fuel for Iran's nuclear reactor at Bushehr, which is being built with Moscow's help.

The United States accuses Iran of pursuing a clandestine nuclear-weapons program. Iran says its nuclear program is for peaceful purposes only, and recently signed a protocol to the Nuclear Non-Proliferation Treaty to give international inspectors greater access to its facilities.

Mr. Bolton is also expected to review the status of implementing the 2002 Strategic Offensive Reduction Treaty, which calls for substantial reductions in the U.S. and Russian strategic nuclear arsenals.