An agreement between Russia and the United States on cooperation in the peaceful use of nuclear energy (aka Agreement 123) officially came into effect Tuesday.

The agreement took force after Russian Deputy Foreign Minister Sergei Ryabkov and U.S. Ambassador to Russia John Beyrle exchanged relevant diplomatic notes here on Tuesday.

"With the entry into force of Agreement 123 there has been turned an important page in our relationship, which allows to increase cooperation in civilian nuclear power," the Russian diplomat told reporters.

"This agreement creates a legal framework, absent until just recently, for implementing a number of programs in the field of peaceful nuclear energy," he added.

Beyrle said "this document allows for the transfer of American nuclear technology, materials and equipment to Russian partners, and thereby opens up opportunities for cooperation on new levels."

Signed on May 6, 2008, the intergovernmental agreement between Moscow and Washington had been frozen as bilateral ties plunged due to the five-day war between Russia and Georgia over the latter's two breakaway regions.

It later then was invigorated as U.S. President Barack Obama targeted the resetting of relations between Russia and the United States as one of his top foreign priorities.