NATO leaders meeting in Prague have invited seven former-communist eastern European countries to join the alliance. The decision will stretch NATO's security umbrella from the Baltic to the Black Sea.

NATO Secretary-General George Robertson says the decision to enlarge the alliance eastward was made after all 19 NATO members signaled their approval of the move over the past few months.

Opening NATO's first summit behind the old Iron Curtain, he suggested that the alliance formally invite the newcomers to join the West's premier security organization. "I therefore put it to the heads of state and government of NATO meeting here in the North Atlantic Council that we invite to accession talks with NATO the following nations: Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia. I take it that this is agreed. Thank you very much. The council has so decided," Lord Robertson said.

The newcomers will formally become members of NATO in 2004, alongside Poland, Hungary, and the Czech Republic, the first former communist countries to join the Western defense pact.

Mr. Robertson says the expanded NATO, which will have 26 members and a land border with Russia, will keep its door open to other candidates. Albania, Macedonia, and, most recently, Croatia, have applied to join the alliance, but are not considered to have met the requirements to do so.

Czech President Vaclav Havel, eastern Europe's senior statesman and a former anti-communist dissident, told his colleagues that NATO's decision to expand further into Eastern Europe marks the end of what he called Europe's unnatural division between the old democracies of the West and the post-communist ones of the East. "It is only through this enlargement that a clear signal is given, not only for all Europeans, but for the entire world, that the era when countries were divided by force into spheres of influence, or where the strong were used to subjugate the weaker, has come to an end once and for all," said Vaclav Havel.

With the enlargement issue out of the way, NATO now turns its attention to what many consider the alliance's fundamental challenge: how to remain relevant in a world whose major security challenges are terrorism and rogue states possessing or seeking weapons of mass destruction.

The leaders are expected later Thursday to commit themselves to modernizing their armed forces with the aim of dealing with such new threats. They are slated to approve a U.S. proposal for NATO to set up a 20,000 man rapid response force that can be deployed anywhere in one-week's time.