Barack Obama arrived in Poland late Friday to lead a conference of central and eastern European leaders focused on supporting democratic changes in the Arab world, dpa reported.
Obama, fresh from a G8 meeting in Deauville, France, was scheduled to share a working dinner with 20 presidents from former Communist states, including the leaders of Czech Republic and Ukraine, plus the leaders of Germany and Italy.
Upon his arrival Obama lay a wreath at the Tomb of the Unknown Soldier, where he spoke briefly with Polish soldiers and veterans.
He then placed flowers at a monument to the Warsaw Ghetto Uprising, a Jewish-led effort in 1943 against the Nazi occupation of Poland. There he spoke with representatives from the country's Jewish community and with Poland's chief rabbi, Michael Schudrich.
The US president was to hold talks on Saturday with Polish President Bronislaw Komorowski and Prime Minister Donald Tusk, with energy issues and the stationing of US F-16s on Polish soil on the agenda.
Komorowski said that countries in the region, which experienced the toppling of authoritarian regimes 25 years ago, are now in a position to help other states in the region and the Arab world as they struggle to move towards democracy.
"We are all aware of the strong and weak sides of our transformations ... We can share our experiences," Komorowski said, as he opened a meeting of the heads of state of former Communist countries focused on support for democracy in North Africa and the Middle East.
"We could count on the help of others at the very beginning of the transformations in Poland," he said. "Now we can offer it."
He said that when many Poles hear the phrase "Arab Spring," they are reminded of the changes that shook Poland in the 1980s.
Komorowski added that all the countries in Central Europe traveled the "difficult road from totalitarianism to democracy," and that success would not have been possible without the European Union. Most countries, he said, began to feel safe only after joining the EU and NATO.
"The road to democracy is our shared goal, our shared achievement and our shared challenge," he said.
However, Serbian and Romanian leaders turned down invitations to the conference because Kosovo was attending.
Komorowski said Poland supported EU membership by both Serbia and Kosovo and that it did not mean to push Serbia away by inviting the breakaway province.
Kosovo's 2008 declaration of independence is not recognized by Romania, Slovakia, Cyprus and Greece.
Obama was expected during his visit to announce that some 16 American F-16s will be moved from a US military base in Italy to central Poland, to be stationed there from 2013 on a rotational basis.
Poland is already hosting a US Patriot missile battery. Warsaw's decision to host the system caused tensions with Moscow, who claimed the system was aimed at Russia and not - as the US has said - against Iran.
The visit will also include talks on energy, with Poland hoping the US will invest money in the country's shale gas.
The US Energy Information Administration said in April that Poland had 5.3 billion cubic meters of shale gas deposits - enough to satisfy Poland's need for the next 300 years.