It all started two weeks ago with a suspected Chinese spy balloon, which carried a payload about the size of three buses. A U.S. fighter jet shot it down after it floated across the continent. Then, the U.S shot down a second object: something airborne over Alaska that the U.S. said was likely not a balloon at all. And now, there’s been a third and a fourth object taken down above North America this month, in these cases over Yukon and Lake Huron. Today, Dan Lamothe explains the knowns and unknowns about these objects and what could be driving the decisions to shoot them down. Lamothe covers the Pentagon and U.S. Military for The Washington Post.