Federal officials say they are temporarily grounding Boeing's 787 Dreamliners until the risk of possible battery fires is addressed.

The Federal Aviation Administration said Wednesday it will issue an emergency safety order requiring U.S. airlines to temporarily cease operating the 787, Boeing's newest and most technologically advanced plane.

The agency said it will work with Boeing and U.S. air carriers to develop a plan allowing 787s to "resume operations as quickly and safely as possible." United Airlines is the only U.S. carrier with 787s. It has six.

Only days ago, FAA Administrator Michael Huerta and Transportation Secretary Ray LaHood declared the plane safe.

But after an emergency landing in Japan early Wednesday, two Japanese airlines voluntarily grounded their 787s.

The FAA order applies only to U.S. carriers, but aviation authorities in other countries usually follow the lead of the country where the manufacturer is based. Fifty Dreamliners have been delivered in the U.S. and around the world.