They floated down from the sky Sunday — 2,000 mice, wafting on tiny cardboard parachutes over Andersen Air Force Base in the U.S. territory of Guam.
But the rodent commandos didn't know they were on a mission: to help eradicate the brown tree snake, an invasive species that has caused millions of dollars in wildlife and commercial losses since it arrived a few decades ago.
That's because they were dead. And pumped full of painkillers.
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The unlikely invasion was the fourth and biggest rodent air assault so far, part of an $8 million U.S. program approved in February to eradicate the snakes and save the exotic native birds that are their snack food.
"Every time there is a technique that is tested and shows promise, we jump on that bandwagon and promote it and help out and facilitate its implementation," Tino Aguon, acting chief of the U.S. Agriculture Department's wildlife resources office for Guam, told NBC station KUAM of Hagatna.