UFO fever gripped Washington and began spreading elsewhere in the world Sunday after defense officials closed down another sector of airspace in the Midwest, another “object” was shot down over the Great Lakes, and speculation about the objects shot down over Canada and Alaska Friday ran rampant.

The Federal Aviation Administration temporarily closed down a section of airspace over northern Lake Michigan in the name of “national defense” Sunday. A similar warning was issued Saturday night for a section of northern Montana, where the agency said civilian aircraft should expect to be intercepted if they ventured into the area.

Both closures were rescinded by the agency after a few hours. “NORAD detected a radar anomaly and sent fighter aircraft to investigate,” a statement by the U.S. Northern Command and the North American Aerospace and Defense Command, or NORAD, issued late Saturday said. “Those aircraft did not identify any object to correlate to the radar hits. NORAD will continue to monitor the situation.”

Sunday afternoon, a congressman from Michigan, Jack Bergman, said Defense Department officials confirmed to him that military jets “decommissioned” another aerial object earlier in the day, this time over Lake Huron. “The American people deserve far more answers than we have,” he tweeted.

The latest object was first detected on Saturday evening over Montana, but was initially thought to be an anomaly. Radar picked it up again Sunday hovering over the Upper Peninsula of Michigan and it was going over Lake Huron.

U.S. and Canadian authorities restricted some airspace over the lake earlier Sunday as planes were scrambled to intercept and try to identify the object. The latest object was octagonal, with strings hanging off, but had no discernible payload. It was flying low at about 20,000 feet, one U.S. official told the Associated Press.

Also on Sunday, China reported its own run-in with what it called an “unidentified flying object” over the waters off its Shandong province north of Shanghai. The country’s state-owned Global Times reported that the object was sighted near the coastal city of Rizhao, where maritime authorities warned fishermen to be wary and “assist in taking photos to collect evidence” if the unidentified object fell into nearby waters.

Chinese authorities were said to be preparing to shoot down the object, but there was no official comment from the central government in Beijing on the incident.

On Saturday, the Air Force of Uruguay issued a statement that it was sending a team of investigators to the western department of Paysandú near the border with Argentina to interview witnesses that it said reported seeing “intermittent lights” Friday night.

The United States has now shot down three objects seen floating over North America in the past several days, one in Canada and another in Alaska. The action comes after what was confirmed to be a Chinese surveillance balloon was allowed to drift over the entirety of the U.S. mainland before being shot down by F-22 fighters off the coast of South Carolina February 4.

Authorities have been mum about the nature of the most recent objects destroyed, but in an appearance on ABC’s “This Week” Senator Schumer, the Senate Majority Leader, said the objects are believed to have been balloons as well. They were, he said, much smaller than the balloon shot down over South Carolina.

Officials in Canada were said to be searching remote corners of the Yukon territory in order to retrieve what remains of the object shot down in its airspace. Similar recovery efforts by the American military to retrieve the object in Alaska were said to be hampered by poor weather.

The topic of UFOs dominated the Sunday morning political chat shows, with bombast over the incidents breaking down largely along partisan lines. Mr. Schumer suggested President Biden waited to shoot down the larger Chinese surveillance balloon in order to gather intelligence. He described the decision to wait before eliminating it an intelligence “coup” for the president.

“We got enormous intelligence information from surveilling the balloon as it went over the United States,” Mr. Schumer said. “By shooting it down over water — U.S. waters — only six miles out from South Carolina, we’re probably going to be able to piece together this whole, whole surveillance balloon, and know exactly what’s going on. So that’s a huge coup for the United States.”

The Republican chairman of the House Foreign Affairs Committee, Michael McCaul of Texas, however, suggested that the decision to let the balloon fly over sensitive sights in Montana, Missouri and Nebraska may have done what he called “a lot of damage” to American military interests. He said he was skeptical of assertions from the intelligence community that any damage was “mitigated” during the flyover.

“They say they mitigated it but my assessment, and- and I can’t get into the detail the intelligence document, is that if it was still transmitting going over these three very sensitive nuclear sites,” Mr. McCaul said. “Going over those sites, in my judgment, would cause great damage. Remember, a balloon could see a lot more on the ground than a satellite.”

The Republican chairman of the House Intelligence Committee, Mike Turner, said the incidents have demonstrated that America has neglected to protect its airspace in recent years and that Congress may need to step up its efforts to change that.

“We don’t really have an adequate radar system, and we certainly don’t have an integrated missile defense system. We’re going to have to begin to look at the United States airspace as one that we need to defend,” Mr. Turner said on CNN’s “State of the Union” Sunday. “This shows some of the problems and gaps that we have.”