With the Japanese threat after Pearl Harbor it grew rapidly and played a critical role in fighter and anti-submarine operations in Canadian and American waters during the Aleutian Islands Campaign.

In addition to the new squadrons, new aircraft types came on line replacing the command's remaining Supermarine Stranraers and Blackburn Sharks with Cansos and the Bolingbrokes and Beauforts with the Lockheed Ventura.

Countless training missions and operational patrols bolstered the air activity over the coastal areas but there was not much action until RCAF Western Command was on the look out for General Kusaba's fire balloons that the Japanese called the Fūsen Bakudan Campaign.

In February and March 1945, P-40 fighter pilots from 133 Squadron, Royal Canadian Air Force operating out of RCAF Patricia Bay (Victoria, British Columbia), intercepted and destroyed two fire balloons, On 21 February, Pilot Officer E. E. Maxwell While shot down a balloon, which landed on Sumas Mountain, in Washington State.

5 OTS Heavy Conversion unit stood up at Boundary Bay when 16 B-24 Liberators arrived fresh from American factories.

With the unconditional surrender of Japan the RCAF's Tiger Force bomber squadrons were disbanded before they flew overseas and the total draw down of the Western Air Command was suddenly undertaken.