It has been a rollercoaster week for the Bush administration's plans to build anti-ballistic missile interceptor bases in Central Europe to guard against the future threat of Iranian nuclear attack.

The government of the Czech Republic Tuesday signed an agreement with the United States permitting Washington to build an advanced radar array tracking base for the interceptors on its territory.

U.S. Secretary of State Condoleezza Rice signed the agreement with Czech Foreign Minister Karel Schwarzenberg in Prague Tuesday. "Ballistic missile proliferation is not an imaginary threat," she said.

However, the all-important negotiations with neighboring Poland to build the actual interceptor base on Polish territory fell through Monday when Polish Prime Minister Donald Tusk rejected a generous U.S. offer to boost Poland's air defenses, saying he needed far more U.S. financial and military aid in advance than Washington was prepared to give.

"If the (Russian) threat related to the shield indeed increases, then we need elements such as Patriots on Polish territory, and not just for one year," Tusk said.

The hard-line Polish stance had been signaled well in advance and did not take Bush policymakers by surprise. Although Rice is visiting Bulgaria and even Georgia, a non-NATO member and a former Soviet republic in the remote regions of the Caucasus on the eastern shore of the Black Sea, on her current trip, she pointedly did not plan any visit to Poland in a tacit admission she would not have been able to pressure or persuade Tusk to agree to the BMD base deal.

Tusk's position is based in significant part on fear of neighboring Russia, but it also reflects his own deep political convictions and those of his foreign minister, Radoslaw Sikorski, and his defense minister, Bogdan Klich. All three of them over the past six months repeatedly have publicly expressed their reluctance, if not downright hostility, to allowing the base to be built on Polish territory.

In contrast to his strongly pro-American predecessor, Prime Minister Jaroslaw Kaczynski, Tusk has put improving relations with Russia at the top of his foreign policy and strategic agenda. At the same time, the Poles do not want to outrage American public opinion or the Bush administration, which always has been strongly supportive of Poland, so instead of saying a straight "no" to allowing the BMD base to be built, they have kept upping their negotiating demands on the issue while running out the clock on the talks.

The Poles appear to hope Democratic presidential front-runner Sen. Barack Obama of Illinois will win the U.S. presidential election in November. Obama's most senior foreign policy adviser, former national security adviser Zbigniew Brzezinski, has said the Polish BMD base does not need to be built, and this position is widely shared by Democratic Party leaders in both houses of Congress, who slashed funding for the program by one-third this year.

Tusk's anti-base policy, however, is very popular with the Polish public, who take threats from Russia seriously. Top Russian leaders have warned repeatedly they will respond to the interceptor base being built by targeting their own short-range and intermediate-range ballistic missiles on it, even though the base will house only 10 interceptors -- quite sufficient to try to shoot down a handful of Iranian ICBMs but no threat to the Russian strategic missile forces with their 4,100 nuclear warheads.

When U.S. President George W. Bush held his first one-on-one talks with new Russian President Dmitry Medvedev in Japan Monday at the annual summit gathering of the Group of Eight leaders of the major industrialized nations, he found Medvedev remained as implacably opposed to the BMD bases being built in Central Europe as had been his predecessor, the formidable Vladimir Putin, still holding real power as Russia's prime minister. At last year's annual Munich Conference on Security Policy, on Feb. 10, 2007, Putin warned that building the bases and other clashes of U.S. and NATO policies with Russia could lead to a new Cold War in Europe.

Tusk's continued refusal to agree to U.S. terms for building the BMD base marks a major strategic victory for Putin and Medvedev, and a highly significant reversal of expressed Polish security policies since the collapse of communism.

-- (Part 2: The wider meaning of Poland's BMD base policy)