EDINBURGH, Scotland — Defense Secretary Robert Gates is asking European allies for more troops to help stabilize Afghanistan, where the government is weak, the insurgency is relentless and casualties are mounting.

He got encouragement Thursday from a reliable U.S. ally — Britain.

Success in Afghanistan will require a significant and concerted international effort, said British Defense Secretary Des Browne as NATO defense and foreign ministers from countries operating in the south of Afghanistan gathered in Edinburgh for a conference. In southern Afghanistan, Taliban insurgents have increased attacks in the 18 months since NATO took command of the war.

"We must give the Afghan authorities the support they need to deliver the kind of success that we all recognize is vital, not just for security in Afghanistan, but for security in the wider world," Browne said in a statement.

Browne just returned from a visit to Afghanistan and praised the work of military forces there.

"But military power can only ever be part of the solution," he said. "We must build on our hard-won military gains and go further to help the people of Afghanistan to provide their own security, governance and economic development."