Iran upgraded missile and drone capabilities enough to cause as much as $15 billion in damages on US bases in the Middle East since the war began, according to a new report.

An analysis into the July 17 strike that killed three American service members at the Muwaffaq Salti Air Base in Jordan revealed how well Iran has improved its tactics — to exceptionally devastating and costly degrees, the Wall Street Journal reported.

Unlike previous attacks, July’s nighttime assault directly targeted and hit 19 buildings specifically housing American troops as they slept, according to Journal sources and satellite analysis.

The data indicated that Iran’s aim was growing more precise, with Tehran hitting buildings that were smaller thany those it was able to strike at the start of the war.

The complexity of the attack signaled Iran’s capabilities had been improving, not diminishing, as the Trump administration claimed.

Iran’s heaviest assaults came at the start of the war, when it damaged at least 119 buildings across 13 installations within the first two weeks of the conflict.

While US-Israeli joint airstrikes took out a large swath of Tehran’s missile network, the Iranian attacks continued.

The Journal estimates that Iran has hit another 155 structures, with 13 more military installations suffering damages by the end of July.

More than 20 US service members have died in the Iran war, with another over 400 wounded, according to the Defense Department.

The Pentagon estimates that US bases in the region have suffered at least $5 billion in damages, with the true cost predicted to be as high as $15 billion, the WSJ reported.

That amount is not included in the DoD’s latest war cost estimates, which were recorded at $47.1 billion as of Oct. 16.

While The Defense Department has repeatedly claimed that Iran’s attack capabilities were wiped out, reports indicate that the US military has been pulling personnel out of its bases in the region in recent months.

The move comes as President Trump weighs renewed airstrikes on Iran following Tuesday’s midterm elections, with Iran vowing to retaliate with attacks across the region.

Pentagon officials have warned that the retaliation could be among the deadliest attacks yet, with Iran likely conserving some of its most advanced missiles for the next round of fighting, the WSJ reported.