By Eric Schmitt and Susan Sachs

NATO leaders agreed Monday to help rebuild Iraq's security forces just hours after the American-led occupation forces transferred formal sovereignty to Iraq. But for NATO, many crucial details remain unresolved.

Bush administration officials heralded the training accord and an agreement to increase NATO troops in Afghanistan to bolster security for elections there in September as proof the alliance could overcome divisions to reach consensus on contentious issues far beyond its members' national borders. "We have decided today to offer NATO's assistance to the government of Iraq with the training of its security forces," Mr. Bush and the other 25 national leaders said in a statement.

But the accord fell far short of the administration's original goal to dispatch NATO ground troops to join American-led forces in Iraq, which France and Germany flatly opposed. In a sign of lingering rifts, the statement said the alliance would only "encourage nations to contribute to the training of the Iraqi armed forces." The United States and other allies have provided some training inside and outside Iraq for months, and a three-star American general was recently assigned to help improve the training and equipping of Iraq's 206,000 fledgling security forces. But Iraq's interim prime minister, Iyad Allawi, had appealed to NATO earlier this month for additional help.

NATO planners will now meet with Iraqi officials to decide on training priorities, then match the requests with the alliance or alliance members willing to help. They were also ordered to report back on other possible assistance for Iraqi security institutions. But the timing, location and numbers of trainers involved remain unanswered. "How this training will be worked out I do not know yet," Jaap de Hoop Scheffer, NATO's secretary general, told reporters on Monday. With so much about the NATO training offer still undecided, including which countries might provide it and where, alliance forces already in Iraq are expected to remain the bulwark of security for the foreseeable future.

Mr. Bush and Prime Minister Tony Blair of Britain said the NATO accord showed that the alliance had closed ranks on the need to assist the fledgling Iraqi government, despite the continuing differences among NATO members over the war. "Everybody sitting around the table is hopeful that democracy will serve as an agent of change in this part of the world," Mr. Bush said at a news conference.

NATO leaders opened the two-day meeting under tight security and to the surprising news that the transfer of formal sovereignty in Iraq had been moved up 48 hours. Large swaths of this city of 15 million people were blocked off, and Turkish warships patrolled the Bosporus. Still, hundreds of protesters took to the streets in several locations across the city, but were kept far from the conference center in central Istanbul where NATO leaders gathered. Demonstrators hurled paving stones at police, who responded with batons, tear gas and water cannons. At least 48 police officers and demonstrators were injured, according to the authorities here.

Inside the conference hall, alliance leaders sought to play down tensions over Mr. Bush's Iraq policy, but they remained divided over how to carry out the training plan. Defense Secretary Donald H. Rumsfeld has insisted that the bulk of the training should be conducted inside Iraq. But French and German officials said they would not send instructors to Iraq, preferring instead to train Iraqis at elite military academies in their own countries. President Jacques Chirac of France said any training should be left to individual NATO nations, not the alliance as a whole. "Any NATO footprint on Iraqi soil would be unwise."

Chancellor Gerhard Schrí¶der of Germany said: "The engagement of NATO is reduced to training and only training. We have made clear that we don't want to see German soldiers in Iraq." Some independent security analysts expressed skepticism over the training accord. "It's a political declaration with no real practical meaning," Ivo Daalder, a senior fellow at the Brookings Institution in Washington, said in an e-mail message. "Countries that will provide training were doing so before the declaration, and I doubt that countries that were not will now be so inclined."

Allied officials said training is expected to be coordinated with the efforts now led by Lt. Gen. David H. Petraeus, a former commander of the 101st Airborne Division who is now helping Iraqi officials oversee the training of their forces. Military planners at NATO headquarters in Brussels are already rushing to examine how alliance members can meet the Iraqis' requirements. Senior military officers in Iraq applauded NATO's new commitment to training and suggested approaches the alliance could follow to best meet their needs. "They could individually or collectively contribute everything from slots at their military schools for Iraqi soldiers to sets of equipment to mentors/advisors to drill sergeants," one senior military officer in Iraq said in an e-mail message. "Better yet might be money that the Iraqis could use to buy additional equipment over that which we're purchasing for them."

NATO leaders also announced Monday that the alliance would expand its security role in Afghanistan, fulfilling a political pledge the alliance made months ago. They have cobbled together enough forces and equipment — including helicopters, cargo planes and quick-reaction forces — to honor the agreement. Under the plan, NATO would expand to about 10,000 troops from the 6,500-member force in and around Kabul, the Afghan capital, to operate a total of five provincial civilian-military reconstruction teams.

NATO leaders also announced Monday that the alliance would end its decade-long military operation in Bosnia and replace its troops with police officers and troops commanded by the European Union. NATO would keep a small headquarters in Sarajevo, the Bosnian capital.