JERUSALEM, JANUARY 29

A little-discussed US military desert outpost in the far reaches of northeastern Jordan has become the focus of international attention after a drone attack killed three American troops and injured at least 34 others there.

The base, known as Tower 22, sits near the demilitarized zone on the border between Jordan and Syria along a sandy, bulldozed berm marking the DMZ's southern edge. The Iraqi border is only 10 kilometers (6 miles) away.

The area is known as Rukban, a vast arid region that once saw a refugee camp spring up on the Syrian side over the rise of the Islamic State group's so-called caliphate in 2014.

At its height, over 100,000 people lived there, blocked by Jordan from coming across into the kingdom at the time over concerns about infiltration by the extremist group. Those concerns grew out of a 2016 car bomb attack there that killed seven Jordanian border guards

The camp has dwindled in the time since to some 7,500 people because of a lack of supplies reaching there, according to United Nations estimates.

The base began as a Jordanian outpost watching the border, then saw an increased U.S. presence there after American forces entered Syria in late 2015. The small installation includes U.S. engineering, aviation, logistics and security troops with about 350 U.S. Army and Air Force personnel deployed there.

The base's location offers a site for American forces to infiltrate and quietly leave Syria. A small American garrison at al-Tanf in Syria is just 20 kilometers (12 miles) north of Tower 22. That base is along a Syrian highway leading into Iraq and ultimately Mosul, once a prominent base of the Islamic State group. It's also a potential weapons shipment route over the road for Iran.

U.S. troops long have used Jordan, a kingdom bordering Iraq, Israel, the Palestinian territory of the West Bank, Saudi Arabia and Syria, as a basing point. Some 3,000 American troops typically are stationed across Jordan.

However, the U.S. presence in Jordan risks angering a population that's already held mass demonstrations against Israel's war on Hamas in the Gaza Strip over civilian casualties in a conflict that's already killed over 26,000 Palestinians. Estimates suggest some 3 million of Jordan's 11.5 million people are Palestinian.

Widespread unrest could threaten the rule of King Abdullah II, a key American ally. Jordan initially denied the Tower 22 base existed within its border after the attack Sunday.