Bush will greet the prime ministers of Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia as well as NATO Secretary General Jaap de HoopScheffer for a meeting and ceremony marking the new members' formal adherence to NATO, the White House said in a statement.

The seven countries will officialy become members Monday after handing their accession documents to the United States.

A second ceremony will be held at NATO's Brussels headquarters on April 2 with its 19 current members and the foreign ministers of its seven new members.

It is the first time the alliance, created early in the Cold War in 1949, adds former Soviet states to its membership. This expansion is the largest in NATO's history and moves its center of gravity eastward.

Albania, Croatia and Macedonia are also seeking to join NATO, and Bush will also meet with the prime minister of those states on Monday, the White House said.

"As NATO acts to face the new challenges of the 21st century, the membership of these seven nations in NATO will advance the cause of freedom, and strengthen the Atlantic Alliance, the central pillar of transatlantic relations," the White House said.

"These central and east European democracies have already acted as allies through their strong solidarity and actions in the war on terrorism, and in helping to strengthen peace and democracy in Afghanistan and Iraq," the White House said.

The supreme allied commander, US General Jim Jones, told reporters Friday that NATO "is in the process of one of its most fundamental changes in its history.

"It will be a different organization. It will have a different membership. The Eastern European influence will change the voting demographics. It will bring different views," Jones said.

NATO "is going global instead of regional," Jones added.

The role of NATO, the core of the transatlantic security relationship, is changing, a US State Department official told a Congressional panel earlier this month.

NATO "is transforming itself into an alliance for the 21st century and is playing a major role in the war on terrorism," said Elizabeth Jones, assistant secretary of state for European and Eurasian affairs.

"Our intent is for NATO to do even more to bring peace and stability to Afghanistan and Iraq," she said.

"Afghanistan is the immediate priority," she added. "In Iraq, as sovereignty is transferred to the Iraqi people this summer (June 30), NATO should consider options for a broader role."

The alliance should be prepared to address security issues in the Middle East, Jones continued.

"By the NATO summit in June, we hope the alliance will be ready to offer practical cooperation to interested governments in the Greater Middle East to address common threats," she said.

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