By LOLITA BALDOR Associated Press OTTAWA, Ontario (AP) -- The war in Afghanistan can't be determined by polls, Defense Secretary Leon Panetta said Tuesday, asserting that the US must continue with its strategy in the decade-old conflict despite plummeting American confidence in the war. Panetta said that there is no question that the American people are tired of war. But, he said, the public understands the US is engaged in Afghanistan because of the attacks on September 11, and to prevent al-Qaida from again finding safe havens there to launch attacks. "We cannot fight wars by polls. If we do that we're in deep trouble," Panetta told reporters at a news conference after a day of meetings with Canadian and Mexican defense ministers here. "We have to operate based on what we believe is the best strategy to achieve the mission that we are embarked on. And the mission here is to safeguard our country by insuring that the Taliban and al-Qaida never again find a safe haven in Afghanistan." A New York Times/CBS News poll found that 69 per cent of those questioned believe the United States should not be at war in Afghanistan, and roughly the same amount say the fighting is going either somewhat or very badly. The numbers are up sharply from four months ago, when a bit more than half said the US should not be at war in Afghanistan. The survey reflects a growing frustration among the public and on Capitol Hill with the war, even as the Obama administration tries to map out an exit strategy that would shift the security lead to the Afghans by mid-2013. Canadian Defense Minister Peter MacKay was even more blunt about the poll, saying that as one prime minister of Canada put it: "Polls are for dogs." "This is our generation's war, this is a test of perseverance," said MacKay, whose country has about 1,000 troops in Afghanistan, largely doing training. "Our ability to carry through for the long-term security of not just Afghanistan but the region and also the entire world, so there is a lot at stake. Canada will be there with our NATO partners." Panetta said that a lot of lives have been lost in the war, and "our commitment must be to insure that those lives have not been lost in vain." He said that he and his military commanders are convinced that 2011 was a turning point in the war and that the levels of violence are declining. Panetta was in Ottawa to meet with his defense counterparts, in what US officials hope will be a continuing effort to address shared security threats, including drug trafficking, cyber breaches and border issues. MacKay, Panetta, Gen. Guillermo Galvan Galvan, Mexico's national defense secretary, and Adm. Mariano Francisco Saynex Mendoza, Mexico's Navy secretary, all said that the three countries must improve their defense cooperation because many of the threats that cross the North American borders. The leaders agreed to formalize the process and continue to meet periodically on the issues. In other comments Tuesday, Panetta restated his support for the F-35 stealth fighter, and said the US needs it for the future. But said the US needs to continue to do as much oversight as possible over the contract process. And MacKay said the fighter is still the aircraft that Canada wants, but there will be careful monitoring of the programme. Canada's associate defense minister, Julian Fantino, said earlier this month that his government could back out of its multibillion-dollar plan to buy as many as 65 of the F-35 stealth fighters from the United States. The Lockheed Martin-manufactured fighter is the Pentagon's most expensive weapons programme and it has been troubled by schedule delays and cost overruns. In January, Panetta took the programme off the probation which had been imposed by then-Defense Secretary Robert Gates a year earlier because it was experiencing "significant testing problems." But Panetta has warned that the troubled programme is not yet out of the woods. Ten years in, the total F-35 programme cost has jumped from $233 billion to an estimated $385 billion. Recent estimates suggest the entire programme could exceed $1 trillion over 50 years. The developer of the aircraft, Lockheed Martin Aeronautics Co., is building three versions of the F-35 -- one each for the Navy, Air Force and Marine Corps. The plane would replace Cold War-era aircraft such as the Air Force F-16 fighter and the Navy's F/A-18 Hornet. In outlining next year's defense budget, Panetta said the administration would slow the purchase of the F-35, a step Congress would have to approve.