The top diplomats and defense chiefs of the two countries failed at talks in Moscow on Tuesday to reach an agreement on Washington's plans to deploy a missile shield in Poland and the Czech Republic, which Moscow views as a threat to its own security, but agreed to continue talks.
"Despite yesterday's promises, we have not received any written proposals from the American side," ministry spokesman Mikhail Kamynin said.
U.S. Defense Secretary Robert Gates and Secretary of State Condoleezza Rice put forward proposals to ease Moscow's concerns, and said they would be finalized in writing.
Russian Defense Minister Anatoly Serdyukov said the '2+2' talks had shown the sides' positions remained unchanged, but Foreign Minister Sergei Lavrov called the new proposals put forward by Rice and Gates "useful and important."
After the last round of talks between the four ministers in October 2007, the U.S. sent written proposals that Russia said contradicted the agreements reached at the discussions.
On Tuesday, Rice admitted that there had been some discrepancies between the conceptual ideas put forward at the October meeting and the subsequent written proposals.