Gates arrived at Kandahar Air Base from Kabul, where he called an ongoing operation in Helmand "only one of many battles still to come in a much longer campaign focused on protecting the people of Afghanistan."

The overall ground commander, US General Stanley McChrystal, said Monday that US and NATO troops could take on the Taliban in their spiritual capital of Kandahar this summer.

Gates was expected to meet British Major General Nick Carter, the NATO commander in southern Afghanistan, and award two Silver Stars to American service members.

About 6,000 of the 30,000 additional troops pledged by President Barack Obama in December have arrived in Afghanistan, Gates said, with the rest due to deploy by the end of August.

It is his first visit to Afghanistan since NATO and Afghan troops swept into a former Taliban stronghold in the southern province of Helmand on February 13, in an assault seen as a pivotal test of Obama's bid to turn around the war.

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