(CNN) Once the dust cleared, it turned out that one of the enduring lessons from the past week occurred at about 22,000 feet.

"They work," said Jeremy Binnie, Middle East and North Africa editor at Jane's Defence Weekly, of Iran's air defenses. The incident "highlights that when the Iranians really make investment, it can really count," he told CNN.

"We knew that with ballistic missiles, but it appears the case with air defenses too."

This image released by the U.S. military's Central Command shows what it describes as the flight path and the site where Iran shot down a US drone in the Strait of Hormuz on Thursday, June 20, 2019.

The RQ-4A isn't a clay pigeon. At $110 million each, the Global Hawk needs three people to remotely pilot it and its sensors. Wider in wingspan than a Boeing 737, it has a Rolls Royce engine moving it along at around 500 miles per hour as it hoovers up signals and images normally at 65,000 feet to keep out of the way of surface-to-air missiles. Even if they get too close, it has a radar-warning receiver, a jamming system and releases a decoy, towed behind it.

Read More