In the 1940s and 1950s, the U.S. conducted dozens of nuclear tests on the Marshall Islands. The tests forced people from their homes. When they returned to the islands years later, they were exposed to radioactive material.
Even after the U.S. stopped testing nukes there, it still shipped radioactive waste from nuclear tests in Nevada, and dumped more than 100 tons of it into a concrete dome on one of the Islands. Now that dome is at risk of collapsing because of climate change and rising sea levels.