But American officials did not cite any tangible accomplishments from a day of meetings here that brought together the top diplomatic and defense officials from both Russia and the United States, except for a promise to increase official contacts, including military exchanges. That was viewed as underscoring unresolved disagreements on issues like Syria and missile defense — all rendered more complicated by Russia’s granting temporary asylum to Edward J. Snowden, the National Security Agency leaker…

Progress toward a unified front to address the crisis in Syria was viewed as one litmus test of whether the Americans and Russians were working together. Mr. Lavrov said both sides had agreed to press ahead with a second set of talks in Geneva, and senior Obama administration officials agreed that Geneva was the appropriate forum.

But American officials confirmed that a discussion of who should participate in a next round talks was “ongoing,” without saying whether any progress had been made on the Russians’ insistence that Iran attend. The United States has opposed such a prominent role for Iran in the talks.