National Security Council spokesperson Bernadette Meehan told reporters that the two leaders spoke for "a total of approximately 15-20 minutes".
Although both exchanged fleeting comments at the start of the summit Monday, they did not speak at greater length until Tuesday in a meeting that takes place at a time when the US is threatening further sanctions on Moscow for recognizing the separatist elections that were held in eastern Ukraine nine days ago.
The meeting between Obama and Putin was also confirmed by Kremlin spokesman Dmitry Peskov who said: "The breaks were used several times, more than the two times which had been reported, for a brief conversation with President Obama. It was a short conversation but they touched upon bilateral relations, Syria, Ukraine and Iran."
Speaking at a daily press briefing in Washington Monday, US State Department spokeswoman Jen Psaki accused Russia and the separatists of "blatant violations" of a ceasefire signed in Minsk Sep 5.
Psaki warned that the costs to Moscow would rise if it "continues its destabilising and dangerous actions" in eastern Ukaine in a reference to the escalating tensions in that part of the country following elections Nov 2.
She added: "We condemn Russia's increased militarisation of the Donbas region through the provision of tanks and other heavy equipment to separatists. The OSCE SMM (Organisation for Security and Cooperation in Europe Special Monitoring Mission) monitors have reported the movement of large military convoys of Russia-supplied heavy weapons and tanks to the front lines of the conflict in recent days."
Moscow has repeatedly rejected possible new Western sanctions for its recognition of the elections arguing that Russia "respects the will of the people of Southeast" Ukraine, according to Russian Deputy Foreign Minister Grigory Karasin.