WASHINGTON – The Pentagon said Tuesday that Lithuania would be a “good alternative” to Poland as the site for a U.S. missile defense base if negotiations with the Poles fail.

In talks at the Pentagon, Defense Secretary Robert Gates told Lithuanian Prime Minister Gediminas Kirkilas that the Bush administration's preference is to work out a deal with fellow NATO ally Poland, according to Pentagon press secretary Geoff Morrell. The negotiations over a base that would host 10 U.S. missile interceptors have bogged down in a dispute over the extent of U.S. assistance to the Polish military.

“The Lithuanian prime minister indicated that his government was willing to consider hosting the interceptors, and for that the secretary expressed his appreciation,” Morrell said. “Our position remains the same: Our preference is to work out a deal with the Poles. But prudent planning requires that we simultaneously look at backups, if necessary. Lithuania would geographically serve as a good alternative.”

Polish and U.S. envoys were meeting Tuesday and Wednesday on the U.S. proposal to place 10 missile interceptors in northern Poland, to be linked to a missile tracking radar that Washington would like to place in the Czech Republic. Negotiations on the proposed Czech site are closer to completion.

Asked about Kirkilas' visit, State Department spokesman Tom Casey said the U.S. discusses missile defense with all NATO allies. But, he said, “we are not, at this point, involved in any negotiations on alternative sites because our goal is to conclude an agreement with Poland. If, for some reason, those arrangements don't work out, then I'm sure we'd look elsewhere.”

The Polish Embassy in Washington declined to comment on the talks.

Poland's prime minister, Donald Tusk, said in Warsaw Tuesday that an eventual deal on accepting a U.S. missile defense base must strengthen his country's security.

Tusk dismissed suggestions that negotiations have stalled, distancing himself from remarks earlier in the day by his chief aide, Slawomir Nowak, who faulted the U.S. for a slowdown in talks. Nowak told state radio that “the Americans have toughened their position in talks with our negotiators. We see no progress.”

But Tusk disagreed.

“My government is not acting like a naive enthusiast, but like a hard negotiator with the awareness that we are negotiating with friends and our most important ally,” Tusk said. “But Poland's security is a holy thing, and I will not allow for even the smallest mistake to be committed, and that's why the negotiations aren't as simple as they once seemed.”

Russia has sharply protested Washington's plans, arguing that U.S. military installations so close to its borders threaten its security. Moscow has threatened to aim its own missiles at any eventual base in Poland and the Czech Republic with its own missiles.

The U.S. says the plan poses no threat to the Kremlin's vast nuclear arsenal, and has stressed that the system aims to protect Europe and the United States from possible missile attacks from Iran.

Associated Press writer Monika Scislowska contributed to this report from Warsaw.