U.S. President Barack Obama called his Russian counterpart Dmitry Medvedev on Wednesday. The two presidents agreed the negotiations on a successor treaty for the Strategic Arms Reduction Treaty (START) are nearly complete, the White House said.

The White House made the announcement in a brief statement, saying Obama called Medvedev to thank him for his hard work and leadership on the negotiations, as the two sides have made steady progress in recent weeks.

The presidents agreed that negotiations are nearly complete, and pledged to continue the constructive contacts that have advanced U.S.-Russian relations over the last year.

The United States and Russia are to resume talks on the successor treaty for the START next Monday in Geneva. State Department spokesman P.J. Crowley said the talks "hopefully will arrive at a quality agreement that meets the needs and interests of both sides."

Medvedev said Sunday that "95 percent" of the new treaty was agreed upon by Russia and the United States.

The United States and Russia have been working on a successor to the START that expired on Dec. 5, 2009. However, differences over verification and control arrangements prevented the two sides from producing such a document last year.

U.S. National Security Advisor James Jones and Mike Mullen, chairman of the Joint Chiefs of Staff, visited Moscow last week to meet with Russian officials. Russian Foreign Ministry spokesman Igor Lyakin-Frolov said earlier Wednesday the visit was successful, and it could take just a few weeks to work out a final document.

The START, signed in 1991 between the former Soviet Union and the United States, obliged both sides to reduce the number of their nuclear warheads to 6,000 and delivery vehicles to 1,600.

Medvedev and Obama agreed last July to slash each country's nuclear warheads to 1,500 and 1,675 and delivery vehicles to 500 and 1,000 respectively under a new START treaty.