Poland's prime minister met with the US ambassador Thursday, a day after officials said the two countries tentatively agreed to base American missile defenses in Poland. Prime Minister Donald Tusk and Foreign Minister Radek Sikorski greeted US Ambassador Victor Ashe at the premier's office in Warsaw. The three men shook hands and then retired for 45-minute talks behind closed doors. On Wednesday, Polish and US officials said they agreed on the framework of a deal to place 10 missile interceptors in northern Poland as part of a global missile defense shield. The base would be linked to a missile-tracking radar the US wants to build in the Czech Republic. The Czech government has agreed in principle to the plan, but parliament's approval is still needed. Polish officials on Thursday sought to downplay the tentative deal, however.