The new treaty, which is under negotiation to replace the 1991 Strategic Arms Reductions Treaty (START) is promised to be by the Obama Administration historical in the level of bilateral cuts in Russian and American nuclear arms that it will slash.

A source in the Russian Foreign Ministry told Interfax news agency that it will be “the first substantive discussion” of a new treaty and not “simply an exchange of opinions.”

Assistant Secretary of State Rose Gottemoeller is on her way to Moscow as head of a US delegation preparing the way for President Obama’s visit in July.

START currently places a limit of 6,000 warheads on each side. It is due to expire in December.

The Russian and American presidents agreed during their first meeting in London in April upon an immediate beginning to new START talks. Experts believe that the future agreement will lead to larger arms reductions.