But, Summers said, "no matter how strong you are, you don't get very far without friends."
Former secretary of state Henry A. Kissinger, the other cochairman, said the trans-Atlantic alliance was based on mutual values as well as mutual interests. Describing himself as a strong supporter of the Bush administration, Kissinger said the US-European relationship will be relevant in the future but has to be examined to find ways to make it work better.
The trans-Atlantic split widened even as the report was being issued.
A new government in Spain moved to pull its troops out of Iraq, reversing the strong support its predecessor had given the Bush administration.
President Aleksander Kwasniewski of Poland, a staunch ally in the war, said Thursday that he may withdraw troops early from Iraq and that Poland had been "misled" about the threat of Saddam Hussein's weapons of mass destruction.
Kwasniewski took those statements back yesterday, telling President Bush that the troops would remain there, a spokesman for Kwasniewski said.
But Foreign Minister Dominique de Villepin of France told the newspaper Le Monde that the US-led war has made the world a more dangerous place. "We have to look reality in the face," he said.
Many Europeans assumed malign intent on the part of the administration, and "the conviction that the United States is a hyperpower to be contained has become fashionable in Europe," while pacifism took hold in some parts of the continent, the report said.
The Bush administration, trying to avoid limitations on its actions, spurned offers of help in retaliating against Al Qaeda and its Taliban hosts in Afghanistan, the report said. Many NATO allies, meanwhile, protested about US unilateralism and questioned the Bush administration's insistence that the security of all nations was at risk.
These divisions carried over to the war in Iraq, worsening trans-Atlantic relations to the crisis point, the report said.
"Europeans and Americans must now work together to ensure that the Iraq crisis becomes an anomaly in their relationship, not a precedent for things to come," the report said.
