He said it is just a ploy of the Americans to make the military exercises "acceptable" and "palatable".
Duterte, who opposed presence of American soldiers in Mindanao, said if the US really wants to help in humanitarian work, they have to do it year round with or without terrorism.
He recognized, however, that the American medical missions come here on a seasonal basis.
In November, Duterte rejected an offer for him to become the next defense chief citing his hesitation to work with Americans, among many other reasons. He commended the appointment of former Philippine National Police chief and Public Works and Highways Secretary Hermogenes Ebdane to the post this week as a "good choice".
In December, the American Embassy announced Washington was canceling military exercise with the Philippines because of the row over custody of rape convict Lance Corporal Daniel Smith.
Smith was confined at the Makati City Jail and later hastily transferred to the US Embassy, a move severely criticized by many quarters.
The US exerted pressure on the government, canceling the joint Balikatan war games and threatening to halt other forms of aid.
Press Secretary and Presidential Spokesman Ignacio R. Bunye said on Dec. 23 "the cancellation of the exercises is a setback to the military modernization program, the inter-operability of Philippine and US forces and to the strategic alliance of both countries which is grounded on time-honored ties spanning more than a century."
But the US embassy announced Tuesday its government has decided to proceed with the war games on "dates and places to be announced soon".
Ambassador Kristie Kenney was quoted to have said that the joint military exercises have been planned for all of 2007 but would "focus mainly on humanitarian assistance".
The annual "Balikatan" (shoulder-to-shoulder) war games, opposed by militant groups, are the focus of the two countries' security alliance.
Around 5,000 US soldiers and around 3,000 Filipino troops are engaged in the exercises over two weeks.
In 2006, the war games consisted of command post exercises, field and cross-training activities, live-fire drills and humanitarian and civil assistance such as road repairs and engineering works.
This year's exercise was originally set on Feb. 19 to March 4.