The U.S. delegation during talks with senior Russian representatives in Geneva rejected any possibility of winding down NATO's open door policy for other countries, including Ukraine, the head of the U.S. delegation, Deputy Secretary of State Wendy Sherman, said Monday after the meeting in Geneva.

"We strongly reject Russian proposals for security guarantees, which are simply not accepted in the United States. We will not allow anyone to roll back NATO's open door policy," the head of the U.S. delegation said during a telephone briefing after the meeting with the Russians.

She also noted that Monday's U.S.-Russia Strategic Stability Dialogue was "frank and direct" and lasted about eight hours.