A little-noticed U.S. government study explores what would happen if terrorists got their hands on enough nuclear material to explode a 10-kiloton nuclear bomb, roughly 5,000 times more powerful than the truck bomb that destroyed the federal building in Oklahoma City in 1995. But the city wouldn’t disappear from the map.

“It’s not the end of the world,” said Randy Larsen, a retired Air Force colonel and founding director of the Institute for Homeland Security. “It’s not a Cold War scenario.”…

For the fictional attack the U.S. government studied, the blast zone would extend just past the south lawn of the White House and as far east as the FBI headquarters.

“Few, if any, above ground buildings are expected to remain structurally sound or even standing, and few people would survive,” it predicted. It described the blast area as a “no-go zone” for days afterward due to radiation. But the U.S. Capitol, the Supreme Court, the Washington Monument, the Lincoln and Jefferson memorials, and the Pentagon across the Potomac River were all in areas described as “light damage,” with some broken windows and mostly minor injuries.