President George W. Bush will tell President Vladimir Putin that Russia has nothing to fear from eastward expansion of NATO when the two leaders meet for the first time today.
Mr Bush said the time for talk of "East and West is behind us" and that the US is "no enemy of Russia".
"I believe in NATO membership for all countries that seek it and are prepared to share the responsibilities it brings," he said in a keynote foreign policy speech in Warsaw University yesterday.
However, Mr Putin has described as "unacceptable" the next wave of NATO enlargement, expected next year, to nine former communist Warsaw Pact countries, including three former Soviet republics of Lithuania, Latvia and Estonia.
"I will tell President Putin that Russia is a part of Europe and that is does not need a buffer zone of insecure states separating it from Europe," said Mr Bush.
He added that it was time to "move beyond Cold War constructions".
NATO enlargement plans should not be frustrated by using "nation states as a pawn in the agendas of others", in a clear nod to Mr Putin.
He said the division of Europe in the past was "not a geographical fact but an act of political violence" and that together, NATO and the EU could "erase the false lines that have divided Europe for too long".
Mr Bush welcomed the "consolidation between NATO and the EU and the security it brings", and said that this co-operation would form the basis for mutual security in the future.
Mr Bush's visit to Warsaw was the fourth stop on his European tour that has brought him into conflict with European leaders on defence and environmental issues.
He recalled the visit of his father, Mr George Bush, to Warsaw in 1989, and his father's call for "a Europe whole and free".
His father's wish had been fulfilled in part, said Mr Bush, but he said Russia had more work to do.
"I will tell Mr Putin tomorrow that the path to greater prosperity lies with greater freedom," he said.
He cited Poland as a "bridge to the democracies of Europe" and a beneficiary of democracy, free markets and common security.
Poland joined NATO in the last phase of enlargement in 1999 and has been the staunchest ally of the US in the region.
Mr Bush said he hopes to establish a rapport with Mr Putin at their first meeting today in the Slovenian capital, Ljubljana.
"He doesn't know me and I don't know him very well, [but] I am confident that I will be able to say I have a pretty good feel for the man and he has a pretty good feel for me," he said at a press conference yesterday afternoon.
Despite disagreements on NATO enlargement and missile defence plans, Mr Bush said he hoped to be able to call Mr Putin "a friend" and Russia a "partner and ally".
Also on the agenda will be US worries about reports of proliferation of weapons along Russia's southern border.
Yesterday the German Chancellor sounded a more cautious note on NATO enlargement.
He declined to say whether Germany backed entry of the three former Soviet states so opposed by Russia.
"The door to NATO entry is open. Everything else will depend on whether a country is not just willing, but fit, to join, and whether there is an increase in security," Mr Gerhard Schroeder told the Financial Times Deutschland.