Crucial disarmament talks kick off in Moscow on Tuesday when U.S. Assistant Secretary of State Rose Gottemoeller meets with Foreign Ministry officials to discuss replacing the 1991 Strategic Arms Reduction Treaty, or START I.

Pressure on participants will be high, because Presidents Barack Obama and Dmitry Medvedev agreed last month in London to have a replacement ready when the treaty regulating both countries' Cold War-era nuclear stockpiles expires in December.

In addition, both sides pledged to have a road map ready as soon as July 8, when Obama is due in town for his first visit to Russia.

Gottemoeller said after a preliminary meeting in Rome last month that the negotiations are important for "hitting the reset button" in U.S.-Russian relations.

Mutual ties were affected by fresh setbacks earlier this month when Moscow and NATO traded tit-for-tat expulsions of diplomats over spying allegations and the Kremlin stepped up criticism over the Western alliance's military exercises in Georgia.

The Russian delegation will be led by Anatoly Antonov, who heads the Foreign Ministry's security and disarmament department. Gottemoeller, who headed the Carnegie Moscow Center before joining Obama's administration, knows him very well, officials have said.

No news conference is planned during the two-day talks at the Foreign Ministry, spokespeople for both the ministry and the U.S. Embassy said Monday.

The negotiators' task seems formidable not just because of the extremely tight time frame and highly complex technical issues, but because Moscow wishes to tie in other arms disputes. Washington has said it would like to handle START in isolation to increase the chances of success.

Prime Minister Vladimir Putin has said any new treaty is definitely linked to U.S. plans to build a missile defense system in Poland and the Czech Republic, which Russia opposes. "Russia will naturally always link missile defense with everything that is related to it, including the Strategic Arms Reduction Treaty," Putin told Japanese media last week.

The Foreign Ministry threw another arms agreement into the ring last week when it said Russia was proposing a new version of the Treaty on Conventional Armed Forces in Europe, in which Moscow suspended its participation more than a year ago.

Russia also wants a new cap on the means of warhead delivery to be introduced in the new treaty. The previous U.S. administration planned to equip missiles with non-nuclear warheads and was believed to have been reluctant to cut the number of missiles.

Analysts said it was necessary for Russia to push for combined talks rather than treating each treaty in isolation.

"This is the right thing to do now, because so many unsolved and complex issues are on the table," said Alexander Khramchikhin, an analyst with the Institute of Political and Military Analysis.

Gennady Yevstafyev, a retired general who serves as a nuclear arms expert at the Center for Policy Studies, said Moscow seemed unhappy about the pace with which Washington was tackling the issue.

"The problem is that the U.S. has not been too clear about their concept for the talks," he told The Moscow Times.

He said this could be guessed from Foreign Minister Sergei Lavrov's remarks last week that the talks in Moscow were no warm-up meeting and that they should produce clarity about each side's position.

He added that although negotiations would be difficult, chances for a new treaty were good because both parties have pledged to move ahead. "They are doomed for success," Yevstafyev said.

A new treaty could dramatically cut U.S. and Russian strategic nuclear arsenals to 1,500 each. Figures on the current numbers of warheads differ, but most estimates say both countries have more than 3,000 strategic warheads.