Russian Prime Minister Vladimir Putin is warning that his country will find it necessary to build up its nuclear forces, if the United States doesn't ratify a new arms reduction treaty.

The treaty, called New START, was worked out this year amid praise that it marked a newly cooperative spirit between Washington and Moscow. However, many Republicans in the U.S. Senate are expressing reluctance to ratify it.

Putin, in an interview to be broadcast Wednesday on the CNN television channel, said that if the treaty isn't ratified, "we'll have to react somehow," including deploying new nuclear technology.

In interview excerpts posted on CNN's website, Putin said the treaty is in the United States' best interests and it would take "a very dumb nature" for legislators to ignore that.

Putin's comments come a day after President Dmitry Medvedev made a similar warning to the West on another defense issue, NATO's proposal to build a European missile defense system. Russia has been invited to participate in the system, but substantial questions remain, including whether Russia would be an equal partner with the Western alliance.

"In the next 10 years, the following alternatives await us — either we reach agreement on missile defense and create a full joint cooperation mechanism, or, if we don't reach a constructive agreement, a new phase of the arms race will begin," Medvedev said Tuesday in his annual address to both houses of parliament. "And we will have to make a decision on deploying new means of attack."

In Washington, Republicans reluctant to ratify New START quickly said Tuesday the Obama administration had dealt with some of their misgivings, raising the prospect for U.S. Senate approval of the treaty.

President Barack Obama has insisted that completion of the treaty is a national security imperative, and he argued for the pact at a White House meeting with congressional leaders.

Republicans, led by Sen. Jon Kyl, have rejected the president's contention that the treaty must be dealt with during Congress' current short year-ending session, arguing that the Senate has more pressing business and several issues on the nuclear deal remain unresolved.

Still, the Republicans' positive comments raised the possibility that the treaty might be approved by the end of the year.

Sen. Bob Corker, a Republican member of the Foreign Relations Committee, said Tuesday that Obama administration officials responded late Monday night to several matters raised by Kyl and himself about modernization of the remaining U.S. nuclear arsenal and sufficient funds for safeguarding the stockpile.

The treaty would reduce the limits on strategic warheads held by the United States and Russia to 1,550 for each country from the current level of 2,200 and would establish a system so each country could inspect and verify the other's arsenal.

In addition to their concerns about modernization, Republicans also have argued that the treaty would limit U.S. missile defense options.