Copenhagen, Denmark (CNN) — President Obama said Friday that the United States and Russia are close to forging a new nuclear disarmament treaty “in a timely manner.”

Obama met Friday with Russian President Dmitry Medvedev on the side of the U.N. Climate Change Conference in Copenhagen, and the two leaders made brief public comments.

The Strategic Arms Reduction Treaty, or START, expired this month, and both countries were working to develop a new pact.

“Obviously, our main concern in coming to Copenhagen was to try to move forward with an accord on the issue of climate change. But on the margins of this meeting we thought it was important to continue to build on the excellent relationship that our two governments have developed over the last several months,” Obama said.

“Our main focus today was the START treaty — the new START treaty that we have been negotiating. We’ve been making excellent progress. We are quite close to an agreement. And I’m confident that it will be completed in a timely fashion. And I just want to thank President Medvedev for being a very effective partner in these negotiations.”

The Russian president, noting that the priority in Copenhagen was the climate summit, said it would have been “unreasonable” not to take the opportunity to discuss the START negotiations.

“Our positions are very close, and almost all the issues that we’ve been discussing for the last month are almost closed. And there are certain technical details which we can encounter [in] many agreements which require further work,” Medvedev said.

“I hope that we will be able to do it in a quite brief period of time. The outcome of our efforts will reflect good and close spirit of our relationship that we have established with the new U.S. administration.”