A U.S. delegation was due to arrive in Poland on Tuesday to make an official proposal to modernize the Polish armed forces in exchange for the deployment of 10 interceptor missiles on the Polish territory.
Grzegorz Schetyna, who is also Poland's interior minister, said the U.S. must provide Warsaw with "solid security guarantees" before Poland can agree on the deployment of a missile base on its soil.
Poland is also insisting on the modernization of its armed forces, primarily its Air Force, with financing to be provided by Washington.
However, Schetyna said the $20 million that the U.S. has pledged in financial assistance was a "meager amount."
Washington is hoping to reach an agreement with Poland before President George W. Bush leaves office in January 2009.
The Pentagon's missile shield deployment plans for Central Europe continue to be a major bone of contention in relations between the U.S. and Russia. Moscow considers the project a threat to its national security.
Washington has proposed a range of measures to ease Russian concerns, but Moscow is insisting on the permanent deployment of Russian personnel at the proposed facilities in Poland and the Czech Republic. Agreement has yet to be reached on the issue.
