This only seem like a science fiction thriller plot: U.S. Air Force jets shot four mysterious objects out of the sky within eight days this month, something that hasn't happened before in peacetime. The aerial dramas began when a jetliner-size Chinese spy balloon was detected above Alaska and floated over the country at 60,000 to 65,000 feet for a week before a fighter plane sank it off South Carolina on Feb. 4. Officials think the balloon was intended for surveillance over U.S. bases in Guam and Hawaii, but blew off course.

"The violation of our sovereignty is unacceptable," President Biden said. "We will act to protect our country and we did." Secretary of State Antony Blinken cancelled a trip to China and later told a Chinese official that type of airspace violation "must never happen again." The huge balloon's parts, pulled out of the Atlantic, will help assess China's capabilities. U.S. officials say it does aerial spying over 40 countries. (America also does spying via orbiting satellites.)

After that incident, three smaller objects were shot down Feb. 10-12 in different locations -- "most likely balloons tied to private companies, recreation or research institutions, studying weather or conducting other scientific research," President Biden said two weeks ago. He ordered F-22 fighters to fire missiles because they flew around the same altitude as commercial aircraft.

The president said he asked agencies for "sharper rules for how we will deal with these unidentified objects" to better assess potential risks. Biden added: "But make no mistake, if any object presents a threat to the safety and security of the American people, I will take it down."

U.S. official says: "These unidentified aerial phenomena have been reported for many years, without explanation or deep examination by the government. President Biden has changed all that. We are finally trying to understand them better." -- John Kirby, National Security Council spokesman

White House says: "There is no — again, no — indication of aliens or extraterrestrial activity." – Karine Jean-Pierre, presidential press secretary

UFO activist says: "Yes, we should focus on protecting American airspace from spying. But we shouldn't lose focus on the fact that there really is a part of this [unidentified flying objects] phenomenon that really is a mystery." -- John Greenewald, paranormal investigator in Castaic, Calif.