US military aircraft have joined the battle against wildfires in eastern Washington state, with footage showing Washington National Guard helicopters dropping water over the Modrite and Bradeen Hill fires on August 4.

Cooler weather and calmer winds helped crews make progress around Spokane, but the scale of the crisis is staggering: More than 45,000 blazes have burned nearly 5.5 million acres across the US so far this year, federal data shows.