"One needn't be an expert to understand: if one party wants or would have an umbrella against all kinds of threats, this party would develop an illusion that it is allowed to do anything and then the aggressiveness of its actions will increase numerously, and the threat of global confrontation will reach a very dangerous level," Putin said in an interview with Japanese media on the eve of his visit to Japan.
Moscow has been at loggerheads with Washington over plans to deploy a missile defense system in Central Europe. The United States has signed agreements with the Czech Republic on hosting a radar station and with Poland on the deployment of 10 interceptor missiles by 2013.
Russia says the missile shield would be a threat to its national security while the United States has argued it is necessary to guard against the threat of missile attacks from states such as Iran.
Considering that the current nuclear arms reduction treaty expires this year, Moscow is ready to return to this issue and agree on a new pact, Putin said.
Russia's Foreign Ministry earlier said that the first round of negotiations between Russia and the U.S. on a new nuclear arms reduction treaty would be held in Moscow on May 18-20.
The Strategic Arms Reductions Treaty (START 1), signed in 1991, obliges Russia and the U.S. to reduce nuclear warheads to 6,000 and their delivery vehicles to 1,600 each. The treaty expires on December 5 this year.
In 2002, a follow-up agreement on strategic offensive arms reduction was concluded in Moscow. The agreement, known as the Moscow Treaty, envisioned cuts to 1,700-2,200 warheads by December 2012.
Russian President Dmitry Medvedev and his U.S. counterpart Barack Obama agreed during their London meeting in early April on an immediate start to talks on a new strategic arms reduction treaty.
Russia and the United States possess 90% of the world's nuclear weapons.
Moscow, which proposed a new arms reduction agreement with Washington in 2005, expects the United States to agree on a deal that would restrict not only the numbers of nuclear warheads but also place limits on all existing kinds of delivery vehicles.
Moscow also insists on the effective use of control mechanisms and procedures, "which the previous administration ignored categorically," according to Foreign Minister Sergei Lavrov.
