The US is tracking a suspected Chinese spy balloon, which has been hovering over Montana.
Montana Senator Steve Daines said he feared it was targeting the state's nuclear missile base.
Montana is home to the sprawling Malmstrom Air Force Base, which stores nuclear weapons.
A suspected Chinese spy balloon is operating near a sprawling base that houses 150 Minuteman III intercontinental ballistic missiles.
The large and bright unidentified object was seen first flying over Alaska's Aleutian Islands and through Canada before appearing over the city of Billings, Montana.
A senior US defense official told reporters on Thursday there was "very high confidence" the balloon was Chinese and that it was flying over sensitive sites to collect information.
China later admitted that the balloon belonged to it, but said it was a weather balloon blown off course, and not meant for spying.
Though US officials did not name any potential target sites, or give a precise flight path, Montana is notable for being home to Malmstrom Air Force Base, which houses nuclear missiles.
Montana Senator Steve Daines said he was concerned by the risk to the US nuclear arsenal.
In a letter to the Department of Defense on Thursday, Daines requested a "full security briefing from the administration on this situation."
"The fact that this balloon was occupying Montana airspace creates significant concern that Malmstrom Air Force Base (AFB) and the United State's intercontinental ballistic missile (ICBM) fields are the targets of this intelligence gathering mission," he wrote in the letter, published by Fox News.
"It is vital to establish the flight path of this balloon, any compromised U.S. national security assets, and all telecom or IT infrastructure on the ground within the U.S. that this spy balloon was utilizing," the letter said.
Malmstrom Air Force Base is one of three such bases in the US to contain Minuteman III intercontinental ballistic missiles, a strategic nuclear weapon. The other two are in Wyoming and North Dakota.
Malmstrom maintains 150 intercontinental ballistic missile silos across its 13,800-square-mile complex, according to The Telegraph. The three bases together house America's full arsenal of 400 Minuteman III missiles.
Retired US Air Force Col. Cedric Leighton echoed the senator on CNN, saying that alongside spying on ballistic missile bases, the balloon could also be "looking at the strategic bomber bases that we have in the Dakotas."
"This is something that gives them a chance to perhaps augment their satellite coverage and it is definitely a system that could be collecting a lot of data," he said.
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