MOSCOW, September 1 (RIA Novosti) - The top U.S. general in Afghanistan has called for a revised strategy to defeat the Taliban insurgency, Al Jazeera reported Tuesday.

Four NATO troops were reported killed on Monday in the war-torn Central Asian state.

"The situation in Afghanistan is serious, but success is achievable and demands a revised implementation strategy, commitment and resolve and increased unity of effort," General Stanley McChrystal, who commands the U.S. and NATO forces in Afghanistan, said.

McChrystal commands over 100,000 servicemen, including over 60,000 from the United States, and is expected to have about 70,000 troops at his disposal by the end of the year.

Violence has surged in Afghanistan, with the radical Islamic Taliban group, toppled in a 2001 U.S.-led campaign, staging regular attacks on provincial government officials, police and troops. There were over 70 attacks across the country during the August 20 presidential polls.