WASHINGTON — Military air traffic controllers lost contact with an Army helicopter for about 20 seconds as it neared the Pentagon on the flight that caused two commercial jets to abort their landings^[1] this month at a Washington airport, the Army told The Associated Press on Friday.

The aborted landings on May 1 added to general unease about continued close calls between government helicopters and commercial airplanes near Ronald Reagan Washington National Airport following a deadly midair collision^[2] in January between a passenger jet and an Army helicopter that killed 67 people.

In March, the Federal Aviation Administration announced^[3] that helicopters would be permanently restricted from flying on the same route where the collision occurred. After the May 1 incident, the Army paused all flights into and out of the Pentagon as it works with the FAA to address safety issues.

Brig. Gen. Matthew Braman, the head of Army aviation, told the AP in an exclusive interview that the controllers lost contact with the Black Hawk because a temporary control tower antenna was not set up in a location where it would be able to maintain contact with the helicopter as it flew low and rounded the Pentagon to land. He said the antenna was set up during construction of a new control tower and has now been moved to the roof of the Pentagon.

Braman said federal air traffic controllers inside the Washington airport also didn't have a good fix on the location of the helicopter. The Black Hawk was transmitting data that should have given controllers its precise location, but Braman said FAA officials told him in meetings last week that the data the controllers were getting from multiple feeds and sensors was inconclusive, with some of it deviating by as much as three-quarters of a mile.

“It certainly led to confusion of air traffic control of where they were,” Braman said.

The FAA declined to comment on whether its controllers could not get a good fix on the Black Hawk's location due to their own equipment issues, citing the ongoing crash investigation by the National Transportation Safety Board.

Transportation Secretary Sean Duffy is pushing to have the agency modernize its air traffic control systems and equipment, which has failed controllers responsible for Newark Liberty Internal Airport’s airspace at critical moments in recent weeks.

In the initial reporting on the aborted landings, an FAA official suggested the Army helicopter was on a “scenic route.”

But the ADSB-Out data , which the Army shared with the AP on Friday, shows the crew hewed closely to its approved flight path — directly up the I-395 highway corridor, which is called Route 5, then rounding the Pentagon.

FAA air traffic controllers at the airport aborted the landing of a Delta Air Lines Airbus A319 during the Black Hawk's initial flight toward the Pentagon because they realized both aircraft would be nearing the Pentagon around the same time, Braman said.

Because of the 20-second loss of contact, the Pentagon's tower did not clear the Black Hawk to land, so the helicopter circled the Pentagon a second time. That's when air traffic controllers at the airport decided to abort the landing of a second jet, a Republic Airways Embraer E170, because they did not have a confident fix on the Black Hawk's location, Braman said.

The Pentagon is sending 1,115 additional troops to the U.S.-Mexico border from over half a dozen units across the different services in support of the Trump administration's immigration crackdown, the military announced Thursday.

They will join more than 8,000 troops on active-duty orders who have been part of the mission since late January, though a spokesperson for U.S. Northern Command emphasized to Military.com that not all of those supporting the mission are directly on the border, with some involved in air or maritime missions or even participating from their home station in some capacity.

The additional troops announced this week are considered "ground components," however, and are charged with providing additional logistics, engineering and medical capabilities as part of the military's effort to "gain full operational control of the southern border," according to officials and a Northern Command news release.

Read Next: Some Army Paratroopers Receive Pay Raise -- Funded by Cuts to Training Jumps^[1]

The spokesperson, Air Force^[2] Capt. Mayrem Morales, said that the additional deployment^[3] of more than 1,000 troops was not the result of "any specific event," but rather part of the buildup of troops supporting the mission. When asked when those service members will deploy, Morales said that is still "to be determined."

"Ground units supporting the southern border mission are located across the southern border from Texas to California," she said in an emailed statement. "However, please know that not all announced units may be at the southern border at this time."

In January, Trump administration officials initially considered sending 10,000 troops to support the border mission. As the buildup grows, the administration has increasingly relied upon military assets to fulfill not only its border security aims, but also its deportation efforts.

The military has taken over federal land^[4] along the border where troops can be used to apprehend migrants on trespassing charges. Other law enforcement entities are then meant to arrest, detain and process the alleged trespassers.

On Tuesday, Military.com reported that 190 individuals have been detected in the New Mexico and Texas "National Defense Areas," but federal judges in those states have already begun dismissing more than 100 charges^[5] related to trespassing in these military zones.

Air Force planes have flown migrants off of U.S. soil to other countries as units have held migrants in detention facilities at Naval Station Guantanamo Bay^[6], Cuba. At one point, the administration planned to hold migrants at Fort Bliss^[7], Texas, but NBC reported^[8] last month that those efforts may have fallen through.

Last week, the Department of Homeland Security requested 20,000 National Guard^[9] troops to assist with deportation efforts^[10].

While service members have taken on engineering or security roles -- including patrols on armored Stryker^[11] vehicles -- along the thousands of miles of land that separate the U.S. and Mexico, many also serve in intelligence capacities or even along the coast aboard warships and in helicopters. The New York Times reported^[12] last week that the military deployed two U-2 Dragon Lady^[13] reconnaissance aircraft as well as surveillance drones in support of the mission.

In a phone call, Morales said that as units rotate in or out or if orders get canceled it can be "very difficult" to communicate the exact number of troops who are deployed directly to the border. She added that the effort is considered "all-domain," meaning troops are in the air, sea, on the ground and gathering intelligence, among other tasks.

"The number of active-duty forces will fluctuate as units and personnel rotate in and out of the operation," she said in the email.

The release announcing the most recent deployment of troops did not specify which units they are coming from. Asked if NORTHCOM could say whether they were active-duty troops or which region they are from, Morales said that is also "to be determined."

The troops include 65 augmentees from the Army, Marine Corps^[14], Air Force and Navy^[15] to support the Joint Task Force-Southern Border headquarters; 250 soldiers from a sustainment command; 140 soldiers from a quartermaster field feeding company; 580 soldiers from multiple engineering units; 75 soldiers from a medical unit; and five logistics airmen from Tyndall Air Force Base^[16] in Florida.

Related: More Charges Related to Crossing Military Zones at Border Tossed by Court in Texas^[17]