In an interview with the Cuban media, published on Saturday, Medvedev said he was satisfied in general with the development of Russian-US relations in the past few years as Moscow and Washington signed a number of important agreements, including the new START arms reduction deal, and “American colleagues” actively backed Russia’s accession to the World Trade Organization.

“Frankly, I feel rather comfortable in a dialogue with the US administration and I am sure that my colleague Vladimir Putin feels the same way, but we [Russia and the United States] still have disagreements on several vital issues, including missile defense,” Medvedev said.

The prime minister reiterated that Washington and its NATO allies refuse to accept Moscow’s arguments that the European missile shield in its proposed shape essentially targets Russia and its nuclear potential.

“We have voiced our concerns but the situation has not changed, and the time to find a solution is running out with each passing month,” Medvedev stressed, adding that the crisis could be looming by the end of this decade.

“If we fail to reach an agreement, the consequences for international relations could be very unpleasant because we will be forced to take retaliatory action,” he said. “Any Russian government, any Russian leader will have to take these retaliatory measures simply because our strategic interests demand so.”

Russia and NATO initially agreed to cooperate on the so-called European missile defense system at the Lisbon summit in November 2010.

However, further talks between Russia and the alliance have floundered over NATO’s refusal to grant Russia legal guarantees that the system would not be aimed against Russia’s strategic nuclear deterrent.

NATO and the United States insist the shield is designed to defend NATO members against missiles from North Korea and Iran, and would not be directed at Russia.

The alliance has vowed to continue developing and deploying its missile defenses, regardless of the status of missile defense cooperation with Russia, which remains stalled.

The final phase of the so-called European Phased Adaptive Approach envisions the deployment of US the SM-3 Block IIB interceptors by 2020 “to help better cope with medium- and intermediate-range missiles and the potential future ICBM threat to the United States.”