TEHRAN — Iran shot down a third American MQ-1 Predator drone over the Strait of Hormuz in a single day on Tuesday, highlighting the country’s assertion of control over the strategic waterway as U.S. forces face mounting losses of unmanned aircraft and increasing pressure on their military infrastructure across West Asia.
The Islamic Revolution Guards Corps Aerospace Force said the third MQ-1 was intercepted and destroyed over the Strait of Hormuz by an advanced air-defense system operating within Iran’s integrated air-defense network.
The announcement came only hours after Tehran reported the destruction of two other American MQ-1 aircraft. Iranian media described the latest shoot-down as the third such operation in a single day and the fourth MQ-1 destroyed over the Strait in recent days.
The losses come against a wider backdrop of documented attrition affecting America’s unmanned-aircraft fleet during the war.
The Pentagon’s inspector general, in its first formal assessment of Operation Epic Fury, reported
 that as many as 30 MQ-9 Reaper drones were destroyed between February 28 and June 30. 
The report also documented the destruction or damage of dozens of other American aircraft and hundreds of buildings and structures at U.S. military installations across the region. 
The MQ-9 losses are particularly significant because the Reaper is one of the principal American platforms for long-endurance surveillance and precision strikes.
Separate reporting by The Washington Post found that the United States had lost at least 45 MQ-9 Reapers, or roughly one-quarter of its fleet, during the terrorist war on Iran. 
The aircraft can cost between $30 million and $50 million depending on configuration, putting the potential value of the lost Reapers above $1.3 billion. 
The Pentagon’s official accounting covers only the first four months of the war, while the larger figure reported by U.S. officials extends beyond that period.  
The significance extends beyond the price of individual aircraft.
The Reaper was designed for sustained operations in environments where American aircraft could operate with relatively limited risk. Heavy losses against Iranian air defenses raise questions about the ability to continue using expensive, relatively slow unmanned aircraft in heavily contested airspace.
The pressure has already begun to influence U.S. planning. American officials are examining cheaper and more expendable unmanned systems that can be deployed in greater numbers rather than relying as heavily on a small fleet of expensive aircraft.
That development gives the Iranian claims over the MQ-1 added significance. The Predator is an older generation of the same broader class of long-endurance unmanned aircraft represented by the Reaper. 
Repeated losses over Hormuz would demonstrate that the threat is not confined to one particular American drone model.
The drone losses are only one component of the broader pressure facing American forces.
A Pentagon inspector-general assessment released Monday found that Iranian attacks damaged or destroyed hundreds of buildings and structures at U.S. bases in Kuwait, Bahrain, Qatar, the United Arab Emirates, Saudi Arabia, Iraq, Oman and Jordan. 
The attacks forced U.S. Central Command to shift personnel, assets and storage facilities.  
The damage to the U.S. Navy’s regional infrastructure in Bahrain was particularly consequential. The Pentagon watchdog said the destruction created significant challenges in establishing alternative naval bases and support ports, forcing the United States to rely more heavily on the remote Indian Ocean base at Diego Garcia.
That relocation has lengthened supply cycles to as much as 14 to 18 days, complicating the movement of fuel, ammunition, spare parts and other supplies to forces operating around the Persian Gulf. 
The report also found that the war produced significant shortages in key U.S. munitions. The Pentagon spent more than $22 billion on munitions during the first four months of the war, while industrial bottlenecks involving rocket motors, explosives, propellants and skilled labor complicated efforts to replenish stocks.  
The cumulative effect has raised concerns inside the American military about its ability to sustain a prolonged high-intensity campaign.
Two U.S. officials familiar with military operations told The Intercept that sustained Iranian attacks on American bases and warships have severely strained military readiness. One official warned that continued pressure could eventually lead to a “breakdown” in the military’s ability to sustain the war.
The officials cited depleted defensive-munition stocks, casualties, maintenance problems, prolonged troop deployments and increasingly difficult logistics.