U.S. Sen. John Thune of South Dakota says the Air Force has approved a proposal to establish an enormous bomber training area over the Northern Plains.

Thune said Friday that federal aviation regulators will now examine the plan to expand the Powder River Training Complex over the Dakotas, Montana and Wyoming. If the FAA approves the proposal, it would become the largest training airspace over the continental United States.

It would be used by B-1 bombers at Ellsworth Air Force Base in South Dakota and B-52 bombers at Minot Air Force Base in North Dakota.

Thune has said the expansion will help prevent the closure of Ellsworth, improve national security and save on fuel costs.

Critics have said the bombers would disrupt rural communities and businesses, and scare livestock.