Afghanistan ? Despite a rise in insurgent violence this spring, U.S. Defense Secretary Robert Gates said Sunday he is convinced that American and NATO forces are making steady progress against the Taliban.

“I think actually things are slowly, cautiously headed in the right direction,” Gates told reporters. “I’m concerned to keep it moving that way.”

He spoke during a flight to the Afghan capital from Singapore, where he attended a security conference. The Pentagon chief had urged Asian nations to provide more troops or other forms of support for Afghanistan.

For months, Gates has expressed concern about possible reversals in Afghanistan, which still lacks a self-sustaining military and suffers from the unmet expectations of building an effective central government.

On Saturday, suspected militants ambushed a NATO convoy in eastern Afghanistan, killing two members of the alliance and wounding seven troops, while 15 suspected militants were killed by police, officials said.