File photo of the Nexen building in downtown Calgary

 
File photo of the Nexen building in downtown Calgary
The Nexen building is seen in downtown Calgary, Alberta, July 23, 2012. In September 2012, two months after China's state-owned CNOOC Ltd made an unexpected $15.1 billion bid for Canadian energy company Nexen Inc, Canada's spy agency told ministers that takeovers by Chinese companies may threaten national security. REUTERS/Todd Korol/Files
Tags: Energy , Spy