U.S. shot 3 objects out of the sky in 8 days. What to know.

Three unusual aircraft have been shot down by U.S. fighter jets over North America this month, incidents that have alarmed U.S. and Canadian lawmakers and ignited debate over the safety of the continent’s skies.

All three, which officials say violated Canadian and American airspace, were downed by F-22s, and debris is being analyzed by experts to glean more details.

Here’s a timeline of what happened and everything we know about the objects so far.

The first

Feb. 4: Chinese surveillance balloon, shot down off South Carolina

On Jan. 28, a mysterious floating object entered Ameri- can airspace. U.S. officials did not acknowledge the balloon publicly until Feb. 2.

On Jan. 30, the balloon entered Canadian airspace before floating back over the United States on Jan. 31.

On Feb. 1, President Biden authorized the mili- tary to take down the balloon, instructing the Pentagon to act “as soon as the mission could be accomplished without undue risk to American lives.” With a single missile, an F-22 Raptor shot down the balloon off South Carolina’s coast on Feb. 4.

The U.S. intelligence community identified the object as a Chinese spy balloon.

The second

Feb. 10: “High-altitude object” downed over Alaska

A pair of F-22 Raptors took down an object roughly the size of a small car over the coast of northeastern Alaska on Friday. Biden was notified about the second object the day before and ordered the hit, National Security Council spokesman John Kirby said.

The Pentagon said the object posed a threat to civilian air traffic because it operated at an altitude of 40,000 feet. It was shot down and landed in freezing, territorial waters. Kirby said the military action was taken out of an “abundance of caution” and that officials do not know where the object came from or why it was floating in U.S. airspace.

The third

Feb. 11: ‘Cylindrical’ object shot down over Canada

An F-22 Raptor shot down a “high-altitude airborne object” over Canada’s Yukon territory on Saturday, the third craft to be intercepted by the military in eight days.

Canadian Defense Minister Anita Anand said the mysterious object was “cylindrical in nature.”

An AIM-9X Sidewinder missile was used to down the object following a discussion between Defense Secretary Lloyd Austin and Anand, said Air Force Brig. Gen. Patrick Ryder, a Pentagon spokesman.

Canadian Prime Minister Justin Trudeau said Saturday on Twitter that he had spoken to Biden and ordered the takedown of the object, which “violated Canadian airspace.”