Kabul, Afghanistan ? The United States is pouring $83 million into upgrading its main military bases in Afghanistan, an Air Force general said Monday in a sign that American forces will likely be needed in the country for years to come as al-Qaida remains active in the region.

Meanwhile, in a reminder of the instability still facing the 25,000 foreign troops in the country, a roadside bomb hit a Canadian Embassy vehicle and another car in Kabul, injuring at least four people.

U.S. Brig. Gen. Jim Hunt said the millions were being spent on construction projects already under way at Bagram, the main U.S. base north of Kabul, and Kandahar in the south. Both are being equipped with new runways.

“We are continuously improving runways, taxiways, navigation aids, airfield lighting, billeting and other facilities to support our demanding mission,” Hunt, the commander of U.S. air operations in Afghanistan, said at a news conference in the capital.

Afghan leaders are seeking a long-term “strategic partnership” with the United States, which expects to complete the training of the country’s new 70,000-strong army next year, but it remains unclear if that will include permanent U.S. bases.

U.S. commanders have said they may cut their 17,000-strong force this year if a Taliban insurgency wanes. But they say the Afghan government remains vulnerable and some kind of U.S. presence will be needed for years.

In an interview with CNN’s “Late Edition,” Army Gen. John Abizaid, the commander of U.S. Central Command, said fresh skirmishes along the Pakistani frontier showed “the fight is not out of the Taliban completely, and not out of the al-Qaida people that are operating in that region.”