President Bush began a quick visit Tuesday to shore up ties with Europe as the White House said the capture and killing of two American soldiers in Iraq was a "reminder that this is a brutal enemy that does not follow any of the rules."

Bush and his wife, Laura, stepped off Air Force One on a warm evening after a flight from Washington.

The administration also issued a fresh warning that North Korea will face diplomatic consequences if it moves ahead with a test launching of a long-range ballistic missile.

"A lot of folks are sending messages to the North Koreans that this would be a bad idea, they shouldn't do it," national security adviser Stephen Hadley said. "And a lot of these countries are going to have ideas about what we do, should North Korea ignore the advice of the international community and go forward with this launch."

White House press secretary Tony Snow said North Korea was getting the message about consequences even if the penalties are not spelled out. "Doesn't mean they don't hear it, just means you don't."

Hadley and Snow spoke as Bush flew to Vienna, Austria, for a meeting on Wednesday with leaders of the 25-nation European Union. Bush wants Europe to eliminate agricultural subsidies so that talks for a global free-trade pact can move forward. And he wants European nations to make good on pledges of financial assistance for Iraq's reconstruction.

Bush also hoped to shore up a united front in opposition to Iran's nuclear ambitions.

Speaking with reporters on Bush's plane, Hadley said it appeared that two bodies found late Monday were those of U.S. soldiers who disappeared last Friday in Iraq.

"I think it's a reminder that this is a brutal enemy that does not follow any of the rules," he said. "It attacks civilians for political gain. It provokes sectarian violence and it really follows no rules of warfare. It's a very brutal enemy and it's a reminder to all of us about what we're up against, and obviously, you know any loss of life is a source of great regret."

The president is visiting a Europe where widespread aversion to his foreign policy — and even his personal style — reduce his leverage to make demands.

Chief among the complaints by the European populace and many leaders is the Iraq war. The opposition to Bush's decision to invade there has been intensified by a host of other concerns: the U.S. detention center for terror suspects at Guantanamo Bay, Cuba, including recent suicides; allegations of abuse at the Abu Ghraib prison in Iraq; the reported existence of secret CIA prisons worldwide; and an alleged massacre of unarmed civilians in the Iraqi town of Haditha.

A survey conducted in 15 European countries by the Pew Research Center for the People & the Press, released last week, showed America's trans-Atlantic image problems. Favorable opinions of the United States this year ranged from a high of 56 percent in key U.S. ally Britain to a low of 23 percent in Spain.

Pro-U.S. sentiment is stronger in much of formerly communist East Europe. So Bush is pairing his Vienna stop with a visit to a relatively new democracy, Hungary.

When his plan to travel to Kiev from Vienna was scotched because of Ukraine's difficulty in forming a new government, it was hastily replaced with a stay in Budapest to commemorate — four months early — the 50th anniversary of the 1956 Hungarian revolution.

The uprising against communist rule there was brutally crushed when Soviet troops overran the country. The communist regime wasn't ended until 1990.

Bush planned meetings with a raft of the country's leaders, beginning with President Laszlo Solyom. Then he was placing a wreath at the Eternal Flame Memorial that honors those who died in the bloody 1956 revolt and delivering a speech billed as the highlight of the trip.

The agenda recalls Bush's trip to Europe a year ago. Then, he participated in a wreath-laying at an obelisk in Riga, Latvia, that represents the resistance to communism, and delivered an ode to the power of democracy before tens of thousands in the same square in Tbilisi, Georgia, where citizens celebrated the Soviet Union's fall.

On Monday, he made clear that he believes some nations in Europe have much to copy in their neighborhood's newest democracies. Bush pointedly expressed gratitude for Eastern Europe's steadfast partnership on Iraq.

"A free and sovereign Iraq requires the strong support of Europe," he said. "And some of the most important support for Iraqis is coming from European democracies with recent memories of tyranny: Poland and Hungary and Romania and Bulgaria and the Czech Republic and Slovakia, Georgia, Ukraine, Latvia, Lithuania and Estonia."

In Austria, where Bush is the first American president to visit in 27 years, police were on alert for possible violent anti-Bush demonstrations. And Austrian Chancellor Wolfgang Schuessel, whose country holds the rotating EU presidency, planned to urge Bush to shut down Guantanamo.