Iran-based militias' drone attacks on US posts in Syria-Jordan send Pentagon scrambling for cover

The lethal drone attack on Sunday in Jordan was the third hit in six months on the base known as Tower 22, highlighting a gap in US defences that the Pentagon is scrambling now to fill.

At Tower 22, there were two previous attacks by one-way drones, according to a Defence official, who was not authorised to comment publicly.

Sunday's attack by a one-way drone killed three US troops and wounded at least 34 more at the base on Jordan's border with Syria.

The White House has blamed Iranian-backed militias for the attack, which have become increasingly dangerous in recent weeks. More than 150 such attacks targetted US bases in the Middle East since Israel's invasion of Gaza, media reports said.

Sunday's attack was the first ever to kill US troops, and President Joe Biden and the Defence Secretary Lloyd Austin have vowed retaliation at a "time and place of their choosing".

At Tower 22, there were two previous attacks by one-way drones, according to a Defence official, who was not authorised to comment publicly.

The drone on Sunday detonated its payload of explosives near living quarters at the logistics base where about 350 US soldiers and airmen are based.

One-way drones hit a target without an operator in charge to steer them after launching, according to the Army.

In July, the Pentagon's Joint Counter-small Unmanned Aircraft Systems held tests in Arizona for weapons to destroy one-way drones. The event was held after an analysis determined that there was a gap in defences for the "emerging threat" of one-way drones, according to an Army's new release.

High-powered microwaves showed promise in knocking down the drones, Army Major General Sean Gainey, Director of the counter-drone office, had said at an event in November in Washington then. They can also be shot down with missiles, but it will take a variety of defences to counter the threat.

"There isn't a silver bullet solution out there," Gainey added.

President Joe Biden blamed Iran for Sunday's attack, a charge the Pentagon has been making for months. The administration has accused Iran of training and equipping the militants to use drones, rockets and missiles in their attacks throughout the Middle East, USA TODAY report said.

NATO Secretary General Jens Stoltenberg said on Monday during a meeting with Defence Secretary Lloyd Austin and Air Force General Charles Q. Brown, Chairman of the Joint Chiefs of Staff, that Iran was behind the attack and those by Houthi militants in Yemen.

"Iran continues to destabilise the region, this includes backing terrorists who attack our ships in the Red Sea and the US is leading international efforts to end these attacks," Stoltenberg said, according to a press pool report.

The emergence of one-way attack drones suggests the use of improvised explosive devices, the number one killer of US troops during the wars in Iraq and Afghanistan.

As with drones, militants used cheap, often off-the-shelf materials to build weapons that exploited Pentagon vulnerability, military experts said.

With IEDs, the weakness targetted was the thin armour and flat bottom of Humvees. Today, that weakness is protecting the airspace over what can be sprawling bases in the desert from small, cheap drones.

At the height of the war in Afghanistan and Iraq, a decade ago, the Pentagon launched an office similar to Gainey's -- the Joint IED Defeat Organisation -- and spent tens of billions of dollars on efforts to protect troops from roadside bombs, including more than $45 billion for Mine Resistant Ambush Protected trucks to replace Humvees, media reports said.

Gainey, according to a Pentagon account of his speech in November, said all troops will likely be required to defend against drones as they will shape the future battlefield. Tragically, the future of warfare appears to have arrived for US troops.