US President Barack Obama takes part in a group photo following a meeting with Central and Eastern European Leaders at the Presidential Palace in Warsaw June 3, 2014. [Photo/Agencies]

WARSAW -- A meeting of the presidents of Poland and the United States -- Bronislaw Komorowski and Barack Obama -- with Central and Eastern European countries' leaders was held on Tuesday at the Presidential Palace in Warsaw.

The topics of the meeting include the Ukrainian crisis, ties with Russia and security in the region, as well as energy security, according to the President's Chancellery.

Invitations to the meeting were extended to the presidents of Lithuania, Latvia, Estonia, the Czech Republic, Slovakia, Hungary, Romania, Bulgaria and Croatia -- all of them NATO members.

Opening the meeting, Komorowski said, "Security, like freedom, are not granted forever. They must be constantly nurtured, constantly strengthened.

"We are doing this in NATO, showing to ourselves and the world that freedom demands effort and frequently strength," Komorowski said.

Commenting on the Ukraine crisis, Komorowski voiced appreciation for NATO's increased presence in Central and Eastern Europe.

Calling NATO's response to the situation in Ukraine "a common experience of importance for solidarity and security," the Polish president expressed hope that NATO members will continue to work towards strengthening the Alliance in face of "the crisis immediately beyond NATO's eastern frontier."

In his address, Obama stated that the United States "stood shoulder to shoulder" with its NATO allies, assuring Central Eastern European leaders that "no one will take away what you have built in the past 25 years".

Obama said that in face of Russia's activity in Ukraine, NATO was raising its presence in the region.

Addressing energy fears connected with the Ukraine crisis, the US president said the United States planned to export more gas on the international market.