|President Obama: "Re-set with Russia has reduced tensions"|
US President Barack Obama has reaffirmed relations between the US and Poland, as his six-day tour of Europe drew to a close.
He praised Poland's economic growth and its support of pro-democracy movements in North Africa and the Middle East.
Mr Obama also said the shelving of his predecessor's plan to build a missile defence shield in Poland did not put the country or region at risk.
Poland PM Donald Tusk said 0he had been reassured by Mr Obama's words.
In a brief press conference with Mr Tusk, Mr Obama said Poland was "one of our strongest and closest allies and a leader in Europe" and "a living example of what is possible when countries take reform seriously".
He praised efforts by members of Poland's Soviet-era pro-democracy Solidarity movement to offer support to Egypt's post-revolution government.
The BBC's Stephen Evans in Warsaw says Polish leaders had been hoping Mr Obama would rectify what many saw as a slight, when he cancelled President George W Bush's missile shield plan as part of efforts to "reset" US relations with Russia.
Many in Poland were disappointed when the US decided not to go ahead with the shield on Polish soil, says our correspondent, reading is as deference to Russia and as a sign of a lack of commitment to Poland.
Mr Obama repeated his insistence that the strategy was about reaffirming the Nato principles of mutual defence, saying it allowed their two countries to deal with shared threats.
"Nato is the strongest alliance in history primarily because it has a very simple principle - that we defend each other," he said.
"What we want to do is create an environment in this region in which peace and security are a given - that's not just good for this region, it's good for United States of America. We will always be there for Poland."Air training
Mr Tusk said Mr Obama's words "give us the sense that together we work for the purpose of Polish security" and that the US strategy was "the best way to guarantee security for Poland".
The two countries also announced plans to hold high-level bilateral business meetings to promote ways of boosting economic growth.
Mr Obama said they had discussed co-operation on "a range of clean energy initiatives" including natural gas projects and nuclear power.
Poland has reserves of shale which hold natural gas.
Our correspondent says Germany and Russia do not want those reserves opened up, Germany for environmental reasons and Russia perhaps because it currently exports much gas to the whole region.
He says the hope in Warsaw was that Mr Obama would support the opening of the shale reserves, ideally with the help of American energy companies.
The US had already announced one new initiative on security - to set up a US air detachment in Poland to train Polish personnel.
However, Mr Obama has not granted Poland's desire for a visa waiver for its citizens travelling to the US.