US and Canadian defense chiefs on Thursday vigorously defended the F-35 fighter jet program, despite criticism over costs and technical delays.

Amid a partisan feud in Canada over the government's plans to buy the stealth warplanes, US Defense Secretary Robert Gates said the continued support of Ottawa and seven other international partners for the project was "very important."

"My hope is that for all of our sakes that all of the partners cooperate to move forward with us on this program," Gates told a joint press conference with his Canadian counterpart, Defense Minister Peter MacKay.

The Pentagon sees foreign partners as crucial to keeping costs under control for the radar-evading fighter, which has been dogged by rising costs and technical glitches.

Gates cited steps taken last year to rectify problems with the F-35 and said he was now satisfied with the program's progress, saying there were no cost increases for the program this year.

MacKay accused critics of the plane of playing a political "game" and warned that scrapping the purchase of 65 F-35 fighter jets could mean grounding Canada's air force in 2020.

The F-35 fighter, billed as the backbone of the future US combat air fleet, has become the most expensive weapons program ever and is now expected to cost the United States $382 billion, for 2,443 aircraft.

The two defense chiefs also discussed the war in Afghanistan, where Canada plans to withdraw combat forces from the south in July.

MacKay said Canada was scouting locations near Kabul to host 950 military trainers, as it continues talks with Washington and NATO about what sort of training is required.

Canada plans to send the military trainers to a base in Kabul until 2014 in a non-combat role to advise Afghan soldiers.

Canadian troops have spent nearly nine years fighting insurgents as part of NATO's International Security Assistance Force, a mission that has claimed the lives of more than 150 Canadian soldiers.

The two also said they discussed expanding Canada-US military cooperation in the Arctic and offering joint maritime security assistance to Caribbean allies.

Gates was due to meet both his Canadian and Mexican counterparts but Mexico's secretary of national defense, General Guillermo Galvan Galvan, could not attend due to illness.

An earlier attempt at a three-way meeting of the defense chiefs in July had to be called off because of violence in Mexico.

MacKay provoked laughter during the press conference when he made a reference to the US states of Oregon and Washington, recalling a recent flub he made during a chat with former California governor Arnold Schwarzenegger.

MacKay had observed that Canada and California "share a border." In fact, they are separated by Washington and Oregon states.