(Adds more quotes, background)

By Patryk Wasilewski

WARSAW, July 9 (Reuters) - Russia's angry response to U.S. plans to build a missile shield underlines the need for Europe to seek closer security ties with the United States, a top aide to Polish President Lech Kaczynski said on Wednesday.

Russian President Dmitry Medvedev said in Japan on Wednesday that Moscow was very upset after Washington signed a deal with the Czech Republic on placing a tracking radar on Czech soil as part of the shield project and would consider how to retaliate.

Washington also wants to install 10 interceptor missiles in Poland, but Warsaw has sought in return billions of dollars in U.S. investment to upgrade its air defences. Last week Poland rejected a U.S. offer as insufficient and talks are continuing.

"(Russia's reaction) proves we need to strengthen our alliance with the United States because beyond our eastern border there are politicians who use a language we thought had vanished many years ago, the language of might and imperial ambitions," presidential aide Michal Kaminski said.

"It is absolutely unacceptable for one country to threaten another for acts that are not aggressive in character. The eventual construction of the shield is not directed against Russia," Kaminski told a news conference.

NATO allies Poland and the Czech Republic were once part of the Moscow-led Warsaw Pact and remain distrustful of their former communist-era overlord.

Poland's President Kaczynski, a conservative who has long favoured closer ties with the United States, has been critical of the centre-right government's tough negotiating stance over the missile shield.

The United States says the planned shield is needed to protect its European allies against possible attack by what it calls "rogue states", particularly Iran, or by terrorist groups.

Russia, acutely sensitive to any Western military build-up near its borders, views the project as a direct threat to its security and has threatened to point missiles at the Czech Republic and Poland if the deployment goes ahead.

"We are extremely upset by this situation," Medvedev told reporters in Japan during a summit of the Group of Eight leaders also attended by U.S. President George W. Bush. (Writing by Gareth Jones; Editing by Alison Williams)

AlertNet news is provided by