Washington ? President Bush welcomed seven former communist countries into NATO on Monday, emphasizing the alliance as a partnership aimed increasingly at fighting terrorism in Europe and beyond.

The expansion — the second time the alliance has added members since the Soviet Union fell — comes as a changing NATO prepares to send more forces into Afghanistan, considers a future role in Iraq, and works with nations in North Africa and elsewhere to thwart terrorist organizations.

“Terrorists hate everything this alliance stands for,” Bush said in a White House ceremony with representatives of the seven nations. “They despise our freedom. They fear our unity. They seek to divide us. They will fail. We will not be divided. We will never bow to the violence of a few.”

The relatively young democracies that joined the North Atlantic Treaty Organization Monday included three former Soviet republics — the Baltic states of Estonia, Latvia and Lithuania — and three members of the former Warsaw Pact: Bulgaria, Romania and Slovakia. The seventh, Slovenia, was part of the former Yugoslavia. The invitation to join the alliance was extended in November 2002 at the NATO summit in Prague and was approved unanimously by the U.S. Senate last May.

The expansion of NATO from 19 to 26 countries tips the balance of the Atlantic alliance farther eastward — and tends to make the group as a whole more sympathetic to U.S. foreign policy. The seven, for example, backed Bush’s move toward war in Iraq early last year, even as original NATO members France and Germany opposed him.

Bush pointedly noted in his remarks that all seven nations are playing supporting roles for U.S.-led military operations in Iraq or Afghanistan. Bulgaria, he said, provided refueling facilities for aircraft during the 2001 Afghan campaign and has sent more than 400 soldiers to Iraq. Military engineers from Estonia and Latvia are helping clear explosives in Iraq, and forces from Lithuania and Slovakia have served there, he said. Romanian and Slovenian troops have deployed to Afghanistan, he added.

“They understand our cause in Afghanistan and in Iraq because tyranny for them is still a fresh memory,” said Bush, whose statements included a dose of Reagan-era anti-Soviet rhetoric. “When NATO was founded, the people of these seven nations were captives to an empire.”

The alliance’s growing roster has been eyed warily by Russia, which also expressed alarm at NATO’s first expansion in 1999, when the alliance welcomed the Czech Republic, Hungary and Poland.

Bush hinted at a third round of expansion of the 55-year-old security organization, noting that the prime ministers of three NATO aspirants — Albania, Croatia and Macedonia — were in attendance Monday.

President Bush, center, waves with leaders of seven former Soviet bloc nations after a ceremony welcoming them to NATO on the South Lawn of the White House in Washington, D.C. Prime ministers pictured Monday with Bush are, from left to right, Indulis Emsis of Latvia, Anton Rop of Slovenia, Algirdas Brazauskas of Lithuania, Mikulas Dzurinda of Slovakia, Adrian Nastase of Romania, Simeon Saxe-Coburg Gotha of Bulgaria, Juhan Parts of Estonia and NATO Secretary-General Jaap de Hoop Scheffer.