Watch Vladimir Putin's interview on CNN's "Larry King Live" at 9 p.m. ET Wednesday.

(CNN) -- Russia will have to build up its nuclear forces if the United States fails to ratify the New Strategic Arms Reduction Treaty the two countries signed this year, Russian Prime Minister Vladimir Putin warns in an upcoming CNN interview.

"That's not our choice. We don't want that to happen. But this is not a threat on our part," Putin told CNN's Larry King in an interview to air Wednesday. "We've been simply saying that this is what all of us expects to happen if we don't agree on a joint effort there."

U.S. President Barack Obama and Russian President Dmitry Medvedev signed the New START in April. The pact would cut each country's deployed nuclear warheads by approximately one-third, limiting each side to a maximum of 1,550 on no more than 700 launchers, and allow both nations to resume on-site inspections.

He said it would take "a very dumb nature" for the United States to ignore its own interests -- but if it does, "then we'll have to react somehow," including the deployment of new nuclear missile technology.

Obama has called ratification of the treaty an immediate priority, saying it's critical to national security and a cornerstone of U.S.-Russia relations. But it must still be approved by two-thirds of the U.S. Senate, where several leading Republicans have called for a vote to be delayed over concerns about missile defense and modernizing the U.S. nuclear arsenal.

But Putin said that without the treaty, Russia will have to arm itself against what the "new threats" posed by U.S. plans for a European-based missile defense system.

"We have been told that you'll do it in order to secure you against the, let's say, Iranian nuclear threat," Putin said. "But such a threat, as of now, doesn't exist."

Putin served as prime minister under Boris Yeltsin, Russia's first post-Soviet leader, then assumed the presidency when Yeltsin stepped down at the end of 1999. He handed the presidency over to Medvedev in 2008 and returned to the prime minister's office.

Human rights groups have complained that post-Soviet freedoms and independent voices have been squelched under Putin's rule. In one of the U.S. State Department documents released by the website WikiLeaks this week, U.S. Defense Secretary Robert Gates is quoted telling his French counterpart that "Russian democracy has disappeared and the government was an oligarchy run by the security services."

Putin dismissed the complaint, calling Gates "deeply misled" and noting that in two U.S. presidential elections, the ultimate winner had received a smaller share of the popular vote but won with a majority in the Electoral College, where votes are apportioned by state population.

"When we are talking with our American friends and tell them, there are systemic problems in this regard, we can hear from them 'Don't interfere with our affairs. This is our tradition and it's going to continue like that.' We are not interfering," he said. "But to our colleagues, I would also like to advise you, don't interfere either [with] the sovereign choice of the Russian people."

And he told CNN that he would make a "concerted decision" with Medvedev about whether he would seek the presidency again in 2012 when the time comes.

"We'll see. There is still quite time before the elections take place," Putin said. And he said suggestions that he remains the true power in Russia -- Batman to Medvedev's Robin, as one of the leaked cables quoted in The New York Times put it --were "aimed to slander one of us."

"The truth of the matter is, this is about our interaction, which is an important factor of the domestic policies in this country. But to be honest with you, we didn't suspect that this would be done with such arrogance, with such a push and, you know, being so unethically done."

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