The spokesperson dismissed talk that the radar deal was in jeopardy, however, saying that the postponement was merely a matter of "logistics."
She added that the deal had been delayed as U.S. Secretary of State Condoleezza Rice would not be able to arrive in Prague on May 5, as previously announced. It had been expected that Rice would sign the radar deal on behalf of the U.S. during her visit.
The U.S. is planning to modify its X-band radar on the Kwajalein Atoll in the Pacific and relocate it to the Czech Republic as part of its proposed European missile shield, which will also include deploying 10 interceptor missiles in Poland.
Czech Premier Mirek Topolanek announced later on Monday that the deal could be signed in early June. However, the signing of the treaty does not provide a 100% guarantee that the U.S. radar station will actually be deployed on Czech soil. The document has yet to be ratified by parliament and signed by President Vaclav Klaus. Opinion polls also indicate that a majority of Czechs are opposed to the U.S. radar being deployed on Czech territory.
There is also considerable opposition to the deployment plan in the Czech parliament, with the leading opposition force, the Social Democratic Party, demanding a referendum on the issue.
Russia has also spoken out against the missile defense shield plan, saying it poses a threat to its national security.
At a meeting in Moscow last month involving the two countries' top foreign policy and defense officials, the U.S. proposed measures to build transparency and confidence. The possibility of deploying Russian officers at U.S. missile defense locations in Europe was also discussed, but the proposals did not include their permanent deployment, on which Russia has insisted.
Russia has rejected Washington's assurances that the planned missile defense system is designed as protection against possible attacks by Iran and other 'rogue' states.