The U.S. Forest Service has its own fleet of more than 20 air tankers, but has in the past called on the military to provide aircraft to help suppress wildfires.
Blazes that have raged across hundreds of thousands of acres (ha) of forests and grasslands in Washington state and Oregon triggered the call for the two aircraft, Steve Gage, a senior official with the U.S. Forest Service, told reporters in a conference call on Friday.
Chronic drought has also parched much of California, New Mexico and Arizona, heightening the risk and intensity of wildfires.
The two planes, stationed at the National Interagency Fire Center in Boise, Idaho, can carry as much as 3,000 gallons (11,350 liters) of retardant which can be dropped on flames in less than five seconds.
They can be dispatched at a moment's notice to states such as Washington, where a fire raging 120 miles (200 km) northeast of Seattle has destroyed hundreds of dwellings and cut power to thousands.
Okanogan County Sheriff Frank Rogers said 300 homes had been destroyed in the 250,000-acre blaze, dubbed the Carlton Complex Fire, one of many raging in forests from California to Idaho.
In California, a fire that erupted on Friday afternoon quickly swelled to 600 acres across El Dorado and Amador counties in the Sacramento area and remained out of control by 8 p.m. local time.
The call to enlist the planes comes as 10,000 of the nation's 13,000 wildland firefighting personnel are assigned to battle blazes in the Pacific Northwest, said Mike Ferris, spokesman for the National Interagency Fire Center.
The partnership of U.S. fire agencies with the Department of Defense provides for an additional six of the air tankers that can be speedily outfitted to drop retardant, officials said. Those are stationed at an Air Force Reserve base in Colorado and in National Guard installations in North Carolina and California, officials said.
"We're ready to rock and roll," said California Air National Guard Lieutenant Colonel Bryan Allen.
U.S. fire managers said the converted air tankers are used to reduce the intensity and slow the growth of blazes so that firefighters can safely construct containment lines.
In addition to the Department of Defense, fire managers said they were in regular contact with Canadian officials about the possible loan of personnel and aircraft.