Moscow has decided to end its nuclear cooperation program with the US, saying that it no longer needs assistance in safeguarding nuclear sites located in Russia, the Boston Globe reported, citing unnamed sources familiar with the situation.

The decision was made late last year, the newspaper says, citing a three-page agreement signed at the meeting held on December 16. According to the newspaper, officials from the US Department of Energy, the US Department of State and the Pentagon, as well as high-ranking Russian officials took part in the meeting.

The agreement put an end to Russia-US cooperation in protecting weapons-grade uranium and plutonium from being stolen or sold, the newspaper said. The United State has allegedly invested approximately $2 billion in the joint program. Several initiatives were expected to continue at least through 2018.

The partnership, which had existed between the two countries under a host of Cooperative Threat Reduction programs, had been the most effective form of US-Russian cooperation since the end of the Cold War in the 1990s, according to the Boston Globe.

The United States reportedly helped Russia destroy huge quantities of weapons-grade nuclear materials - enough to build hundreds of bombs, the newspaper said. It also assisted in equipping Russian nuclear storage facilities with security systems.

Cooperation between Russia and the United States was frozen across many spheres following Crimea's reunification with Russia. Moscow has denied this allegation, saying the move received the backing of the absolute majority of people in Crimea, most of whom are ethnic Russians.