The downing by the USS Boxer (LHD-4), a Wasp-class amphibious assault ship, of an unarmed Iranian fixed-wing aerial drone over the Strait of Hormuz on Thursday reveals the extent of Iran's unceasing surveillance of the U.S. Navy with its vast fleet of unmanned aerial vehicles (UAV).

Unarmed Iranian UAVs have been spying on Navy warships almost every day since last year, according to Navy accounts, so their presence in the air around U.S. warships is to be expected. The Navy said there have been no reports of armed Iranian drones overflying its warships.

Media reports also revealed that Iranian drones normally keep their distance, and ensure U.S. warships see them. They don’t come close enough to a point where Navy warships will have to shoot them down.

In March, 2018, Rear Adm. Steve Koehler, commander of Carrier Strike Group 9 (CSG-9), which was then patrolling the strait, said CSG-9 encountered large Iranian drones nearly every day.

“I will say that it seems they’re fairly predictable, and they’re flying fairly predictable,” said Adm. Koehler.

“Once they get here, they loiter forever, but they sort of stay at the same altitude and we can sort of keep track. And the fact that they’re unarmed that we’ve seen is good. They’re obviously looking at us, ISR (intelligence, surveillance and reconnaissance), and they have the ability to track us and all those things, but unarmed.”

The admiral noted that even if they’re unarmed, “it’s a safety of flight problem. So no matter what altitude they’re at, we have airplanes operating too. So can we communicate with them in the ground station and will they respond? And we see that they do sometimes and they don’t sometimes."

The Navy has released no reason for shooting down an unarmed Iranian drone this time around, other than to say the UAV approached to within 1,000 yards of the heavily armed USS Boxer.

“At approximately 10 a.m. local time, the amphibious ship USS Boxer was in international waters conducting a planned inbound transit of the Strait of Hormuz,” said a Pentagon statement.

“A fixed wing unmanned aerial system (UAS) approached Boxer and closed within a threatening range. The ship took defensive action against the UAS to ensure the safety of the ship and its crew.”

There's also confusion as to whether this UAV was destroyed by one of the Boxer's RIM-116 Rolling Airframe Missiles (RAM), a small, infrared homing surface-to-air missile (SAM), or if it was disabled and crashed after being jammed by the Boxer's electronic warfare system.

President Donald Trump’s account of the shooting down did nothing to answer these questions.

Trump said Boxer took defensive action against the drone after it ignored “multiple calls to stand down threatening the safety of ship and ship’s crew.” He said the Boxer destroyed the drone in a “defensive action.”

“I want to apprise everyone of an incident in the Strait of Hormuz today, involving #USSBoxer, a U.S. Navy amphibious assault ship. The BOXER took defensive action against an Iranian drone....” tweeted Trump.

““I also call on other nations to protect their ships as they go through the Strait and to work with us in the future.”

Trump said this incident “is the latest of many provocative and hostile actions against vessels operating in international waters.”

The destruction of the drone came only hours after Iran’s Revolutionary Guard Corps seized a foreign tanker it accused of smuggling oil.

The Iranians had earlier shot down a U.S. drone which they said intruded into their airspace; the U.S. said that drone was over international waters.