U.S. President Obama and Russian President Dmitry Medvedev met privately during the climate change summit in Copenhagen, Denmark.
"We are quite close to an agreement," Obama said, saying the two leaders made "excellent progress" on a new treaty to succeed the 1991 Strategic Arms Reduction Treaty that expired Dec. 5.
"(Our) positions are very close" with only "technical details" to be massaged, Medvedev said.
Both leaders called each other "effective partners" when meeting with reporters after their bilateral meeting, and offered holiday greetings.
A White House official said Obama earlier met with Chinese Premier Wen Jiabao and "made progress" on climate change issues.
The official said the two leaders discussed the three issues Obama highlighted during his speech to a climate change assembly earlier -- emissions goals from all major industrialized countries, verification mechanisms and financing for poor countries to address climate change.