WASHINGTON (AP) — Russia will "always hate" U.S. missile defenses because it cannot match them, but that should not stand in the way of ratifying a new U.S.-Russian nuclear arms treaty, Defense Secretary Robert Gates said Thursday.

In blunt language, with the administration's top diplomat sitting beside him, Gates told a Senate panel there is little prospect of Washington and Moscow seeing eye-to-eye on missile defense.

"There is no meeting of the minds on missile defense," Gates said. "The Russians hate it. They've hated it since the late 1960s. They will always hate it, mostly because we'll build it and they won't."

Testifying together, Gates and Secretary of State Hillary Rodham Clinton sought to calm fears voiced by Sen. John McCain about the arms treaty, dubbed New START, which includes a provision that the Arizona Republican said limits future U.S. missile defense options.

Clinton noted the Russian government's statement that it reserves the right to withdraw from the New START treaty if it feels threatened by an expansion of American defenses against ballistic missiles.

"But that is not an agreed upon view. That is not in the treaty," Clinton told the Senate Armed Services Committee. "It's the equivalent of a press release, and we are not in any way bound by it."

Clinton and Gates, joined by Joint Chiefs of Staff chairman Mike Mullen and Energy Secretary Steven Chu, showed a united front in the administration's push for Senate ratification. They argued that the pact, while not perfect, enhances U.S. security without constraining the shape of the U.S. nuclear force.

"It does not infringe upon the flexibility we need to maintain our forces, including bombers, submarines and missiles in the way that best serves our own national security interest," Clinton said.

Gates and Mullen stressed that the treaty, if ratified, would not require the Pentagon to change the size of its nuclear arsenal for seven years. Even then, the changes would be relatively minor, he said.

For as long as seven years into the future the U.S. will keep 720 deployed weapons: 240 submarine-launched ballistic missiles (distributed among 14 submarines); 60 heavy bombers, and up to 420 single-warhead Minuteman III intercontinental ballistic missiles at their current three U.S. bases, Gates said.

Mullen said military leaders feel strongly that the U.S. should use that seven-year interval to assess the global strategic environment before deciding how to drop to the 700-weapon limit called for in the treaty.

The arms treaty was signed in April by President Barack Obama and Russian President Dmitry Medvedev, who is scheduled to visit the White House next week.

The pact would put a ceiling of 1,550 on the number of each country's deployed nuclear warheads, down from the current limit of 2,200. It replaces the 1991 Strategic Arms Reduction Treaty, or START, which expired in December.

To be ratified, the treaty needs 67 votes in the Senate. The Russian parliament hasn't yet acted on it.

Gates also spoke pointedly of Russia's conflicting interests regarding Iran. The subject arose when Sen. Scott Brown, R-Mass., told Gates he was troubled that France and Russia, by maintaining commercial relationships with Iran, were helping it circumvent international sanctions over its nuclear program.

"You've just put your finger on a kind of schizophrenic Russian approach to this," Gates said.

McCain pressed the missile defense point in a lengthy exchange with Clinton.

"Russian leadership have all made this statement that this treaty is contingent on the United States not changing, or qualitatively or quantitatively building up, missile defense systems," he said. "That is bound to be worrisome to anyone."

Clinton said the U.S. has issued its own statement about missile defenses, "making clear that the United States intends, and in fact is continuing, to improve and deploy effective missile defense systems."

Gates echoed her view.

"The Russians can say what they want. If it's not in the treaty, it's not binding on the United States," Gates said.

On a related point, McCain expressed worry at a provision in the treaty that would prohibit either country from converting any underground silo from a launch site for offensive missiles to one for defensive missiles.

He called that provision, known as Article 5, "a clear, legally binding limitation on our missile defense options."

"Now this may not be a meaningful limitation, but it's impossible to deny that it is a limitation, as the administration has said," McCain said.

Clinton responded that it has no practical impact.

"We had no intention of doing that (kind of conversion) anyway," she said, so there was no harm in including it in the treaty.

"We could have had a long list — you know, we're not going to launch from any moving vehicle, like a car or a truck or a cow. I mean we could have said a lot of things that we're not going to do. But the fact is, we weren't going to do them, and we weren't going to do this either."