President Bush is on his way to Ukraine for the start of a four-nation trip that also includes stops in Russia, Croatia and Romania where he will take part in a NATO summit. VOA White House Correspondent Scott Stearns has the story.

President Bush and first lady Laura Bush wave as they board Air Force One, at Andrews Air Force Base, 31 Mar 2008

The president opens his trip in Ukraine, where U.S. National Security Advisor Stephen Hadley says Mr. Bush will celebrate the country's democratic transition following the 2004 Orange Revolution.

"He will express his support for the aspirations of the people of Ukraine to see their country take its rightful place within Europe, including within its transatlantic institutions, as Ukraine continues its process of reform," he said.

While in the Ukrainian capital, Mr. and Mrs. Bush will visit St. Sophia's Cathedral and a public school where they will see a student presentation on preventing HIV/AIDS.

On Wednesday, President Bush goes to Bucharest for the NATO summit where Hadley says the trans-Atlantic alliance will highlight how it is changing to meet the challenges of a new century.

"We expect NATO leaders to take decisions to enhance NATO's capabilities to deal with those challenges, including through enhancing NATO's special operations capabilities, as well as pursuing collective defense against cyber and missile attacks," said Hadley.

Afghanistan tops the agenda in Bucharest. NATO leaders will meet with Afghan President Hamid Karzai and U.N. Secretary-General Ban Ki-Moon as well as officials from the European Union and World Bank.

All 26 members of the alliance have troops in Afghanistan. But some have limited their deployments to safer areas where combat with Taliban militia is less likely. President Bush wants more NATO troops from more member states on the frontlines.

NATO leaders will discuss U.S. plans for a missile defense system in Europe and vote on expanding the alliance to include Albania, Croatia, and Macedonia. They will also vote on accepting applications from Georgia and Ukraine to join the alliance, a move that is opposed by Russia.

After the summit, Mr. and Mrs. Bush travel to Croatia where he will make remarks in Zagreb and take part in a working lunch with leaders from countries invited to join NATO.

President Bush wraps up his trip in the Black Sea resort of Sochi for talks with Russian President Vladimir Putin. They will discuss the U.S. missile defense system, which Hadley says is meant to guard against attack from Iran, not Russia.

"The main issue there is to find a way, in concrete terms, to reassure Russia that the radar and missile installation that is planned in Poland and the Czech Republic are, as we say, about potential threats coming to Europe, coming to Russia, if you will, from the Middle East, and are not aimed at Russia," he said.

President Putin has previously discussed cooperating on radar monitoring potential missile attacks, which Hadley says could be part of an integrated defense system protecting Europe and Russia.

Before he left the White House, President Bush again called on Congress to pass a free trade agreement with Colombia and to expand the circumstances under which U.S. intelligence agents can monitor telephone and computer communications between the United States and suspected terrorists abroad without a warrant.