Shares of defense prime contractor Lockheed Martin have been under siege amid changes in U.S. leadership and questions about the viability of technologies it produces.Now, Canada is questioning its purchase of Lockheed’s F-35 jet fighters,

NDP Leader Jagmeet Singh announced Sunday his party would cancel Canada's contract to buy F-35s from the U.S. and look for companies to build fighter jets in Canada — a proposal that some defence experts say comes with steep costs.