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Army Gen. Stanley McChrystal said in a statement that "success is achievable and demands a revised implementation strategy, commitment and resolve, and increased unity of effort."

McChrystal did not seek more U.S. troops for Afghanistan. White House spokesman Robert Gibbs said future troop increases will be addressed later.

The U.S. has about 62,000 troops in Afghanistan — a record number — and will have 68,000 by the end of the year. In total there are more than 100,000 U.S. and NATO troops in the country. There were roughly 250,000 international forces in Iraq at the height of that war.

McChrystal has focused on counterinsurgency since arriving in Afghanistan in June. Last week, he sent coalition troops a memo saying, "We will not win simply by killing insurgents. … That means we must change the way that we think, act and operate. We must get the people involved as active participants in the success of their communities."

Meanwhile, Defense Secretary Robert Gates warned Monday that American casualties will continue to rise as U.S. troops clash with insurgents. The deaths of two U.S. troops Monday made August the deadliest month in the war with 47 killed.

Gates called improvised explosive devices (IEDs) a key concern. Roadside bomb attacks have reached record levels with more than 800 occurring in July, more than twice as many as in July 2008.

The military is rushing an all-terrain version of the heavily armored Mine Resistant Ambush Protected (MRAP) vehicle to Afghanistan. The first of these trucks will arrive there in October, Gates told reporters Monday. MRAPs have proved to be tens of times safer than other vehicles in IED attacks in Afghanistan, USA TODAY reported in August.

Gates also said the Pentagon has pushed for more spy planes and other intelligence-gathering equipment to snoop on bomb makers. Last year, 75% of the military's spy planes were in Iraq and a quarter in Afghanistan. Now, two-thirds are in Afghanistan and one-third are in Iraq, according to military records.