Czech backers of a missile defence shield said Washington's move to scrap the project is a betrayal of allies and a concession to Russia, but Polish critics of the plan said its abandonment underlines the shortcomings of Poland's own leadership, dpa reported. US President Barack Obama confirmed Thursday that the shield, consisting of a radar station in the Czech Republic and missiles in Poland, was being abandoned. "He performs endless concessions towards Russia, for example. I consider it a betrayal of allies." Jan Vidim of the centre-right Democratic Party told the newspaper Lidove Noviny In Poland, Washington's decision was variously blamed on Prime Minister Donald Tusk and President Lech Kaczynski. "I think that what's going on now is the result of serious mistakes at the end of 2007 and beginning of 2008," Kaczynski said, referring to the period when the Tusk administration negotiated the shield with the United States. Karol Karski, of Kaczynski's opposition Law and Justice party, said the government should resign if it had any honour. But Grzegorz Napieralski, head of Poland's Democratic Left Alliance, pointed his finger at Kaczynski himself. -- SPA