By David Shepardson, Idrees Ali and Andy Sullivan WASHINGTON, Feb 11 (Reuters) - A secret military laser-based anti-drone system prompted the Trump administration to ban air traffic for more than seven hours in and out of the Texas border city of El Paso after U.

The airspace over El Paso's international airport was briefly closed Feb. 11 after the Pentagon disabled drones by Mexican cartels, official said.

Pentagon officials had undertaken planning to use military technology near Fort Bliss, in El Paso, to practice downing drones.

The U.S. military shot down a suspected drone near El Paso; the object was later identified as a party balloon, reports say.

According to news reports, Customs and Border Protection officials used a Department of Defense anti-drone laser weapon to target what they identified as a drone crossing the border from Mexico. The FAA closed the El Paso airport and airspace out of concern that the weapon inadvertently posed a threat to air traffic in the area.

The joint base hosting NORAD headquarters and key forces operating in the Arctic and Indo-Pacific is vulnerable to drone intrusions and surveillance, security forces say.

A new crash course is teaching Marines the ins and outs of drone warfare, from navigation in flight to explosive payloads.