Washington, Sept. 30 : United States Defense Secretary Robert M. Gates has criticized the shock-and-awe strategy of the 2003 Iraq invasion and said the Pentagon''s narrow focus on conventional combat operations proved costly when U. S. ground troops had to switch gears to try to stabilize that country.

According to Gates, the Pentagon bureaucracy failed to respond quickly enough to the military''s need for innovative counter-insurgency operations in Iraq and Afghanistan.

He called for reforms to make the institution more agile and flexible.