Here is what is known about the base:
LOCATION
Tower 22 holds a strategically important location in Jordan, at the most northeastern point where the country's borders meet Syria and Iraq.
PURPOSE
Little is publicly known about the base. But it includes logistics support and there are 350 U.S. Army and Air Force troops at the base.
Tower 22 is near Al Tanf garrison, which is located across the border in Syria, and which houses a small number of U.S. troops. Tanf had been key in the fight against Islamic State and has assumed a role as part of a U.S. strategy to contain Iran's military build-up in eastern Syria.
Tower 22 is located close enough to U.S. troops at Tanf that it could potentially help support them, while also potentially countering Iran-backed militants in the area and allowing troops to keep an eye on remnants of Islamic State in the region.
U.S. TROOPS IN JORDAN
Jordan's army is one of the largest recipients of Washington's foreign military financing.
The kingdom has hundreds of U.S. trainers and is one of the few regional allies that hold extensive exercises with U.S. troops throughout the year.
Since the start of the Syrian conflict in 2011, Washington has spent hundreds of millions of dollars to help Amman set up an elaborate surveillance system known as the Border Security Programme to stem infiltration by militants from Syria and Iraq.
MANY UNKNOWNS
It is unclear what type of weapons are kept at the base, air defenses used, and what exactly went wrong.
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