"There's no better symbol of our desire to work for peace and security than working on a missile defence system."
Kaczynski said: "So it is really a defence instrument, missile defence instrument. And so I do hope that all this project, the whole project will be completed successfully."
The Russian president has never been mollified by that argument and the Kremlin announced on Saturday that Vladimir Putin, the president, had signed a decree suspending Moscow's participation in a post-Cold War security treaty.
In Poland, a survey by a publicly funded institute in Warsaw, said that 55 per cent of Poles oppose putting the base on Polish territory - a drop from the previous month, when 60 per cent were opposed.
Jaroslaw Kaczynski, the Polish prime minister and the president's twin brother, said on Tuesday that the shield offered Poland a way to strengthen its alliance with the US and guarantee its security against a resurgent Russia, thus contradicting what Bush and Lech had said a day earlier.
"The point ... is the status of Poland and the future of our country - whether we end up back again in the place we were for many years or whether we don't end up there,'' he said, referring to the Cold War era, when Poland was controlled by the Soviet Union.
In recent months, Moscow suggested it would target missiles at Europe if the US went ahead with the proposal for the defence system.