Russian Prime Minister Vladimir Putin on Tuesday urged Washington to provide Moscow with data about US missile defense developments as part of an information exchange under a new arms treaty.
Putin's remarks carried by Russian news agencies signaled difficulties in talks between the two nations on a successor to the 1991 Strategic Arms Reduction Treaty that expired on Dec. 5. Moscow and Washington had hoped to strike a deal before the end of the year but problems persist.
Putin's comments also showed that the former Russian president is continuing to shape Russian foreign policy, which under the constitution should be set by his successor, Dmitry Medvedev.
Putin said that Russia is ready to provide the US with some data about its new missiles, but wants the US to share information about its missile defense plans in return.
He said that the arms control talks were proceeding in a positive way and added that Medvedev and US President Barack Obama will eventually decide whether to strike an arms deal.
But Putin warned that a missile defense system would give the US an edge and could erode the deterrent value of Russia's nuclear forces.
"The problem is that our American partners are developing missile defenses, and we are not," he said.
"But the problems of missile defense and offensive weapons are closely linked. ... There could be a danger that our partners would feel totally safe after creating such an umbrella and would do what they want. After the balance is broken, they will become more aggressive."
Obama removed a major irritant in relations earlier this year by scrapping the previous administration's plans to place interceptor missiles in Poland and a radar in the Czech Republic - deployments Russia treated as a threat.
The Kremlin has praised Obama for the decision, but Russian officials have also said they want to know details about what system the US will put in place instead.
"They should give us information about the missile defense, and we will be ready to provide information about offensive weapons," Putin said.
Russia had been pushing for an explicit link in the new treaty between offensive weapons and missile defense. A joint statement in July by Medvedev and Obama linked the two, but the US will be unlikely to accept any missile defense restrictions.