US President Barack Obama and Russian President Dmitri Medvedev agreed in Moscow yesterday to reduce U.S. and Russian nuclear weapons stockpiles by up to a third. Medvedev said during a news conference with Obama at the Kremlin that the two leaders have forged an understanding on a pact to follow up the Strategic Arms Reduction Treaty, known as START.

“We agreed on the levels of carriers and warheads, meaning that this is a very concrete subject,” the Russian president said. “In the mutual understanding, as we have just signed with the president of the United States, it is said that our two countries can have from 500 to 1,100 carriers of strategic arms, and from 1,500 to 1,675 warheads.”

The leaders agreed that offensive and defensive systems should be considered together. The two also adopted a joint statement on anti-ballistic missile programs.

Obama said the meetings helped to correct the “sense of drift” in the relationship between the two nations. Russia damaged the relationship with its August incursion into the former Soviet republic of Georgia.

Still, the two nations must talk and must work together, the leaders said. “We’ve taken important steps forward to increase nuclear security and to stop the spread of nuclear weapons,” Obama said at the news conference.

“We have signed a joint understanding for a follow-on treaty to the START agreement that will reduce our nuclear warheads and delivery systems by up to a third from our current treaty limitations,” Obama said. “This legally binding treaty will be completed this year.”

The leaders also agreed on a joint statement on nuclear security cooperation that calls on the two nations to cooperate in securing vulnerable nuclear materials.