US President Joe Biden said his country will ‘take care’ of the situation with the Chinese meteorological balloon flying in US airspace.
At New York's Hancock Air Force Base, reporters asked the president to comment on the situation using a Chinese airship.
"We’re going to take care of it," the White House pool quoted Biden as saying. He did not clarify his words.
The US Federal Aviation Administration said later on Saturday that it had suspended traffic at three airports "in support of national security efforts."
One of the airports affected is Myrtle Beach International in South Carolina - the state the airship was said to be headed toward.
The FAA also closed the airspace off the coast of South Carolina. Tracking website Flightradar24 showed US Air Force and Coast Guard planes operating in the skies between Wilmington, North Carolina, and Myrtle Beach.
The balloon's arrival in the US comes amid tense tensions between Washington and Beijing, with Secretary of State Antony Blinken cancelling a trip to Beijing over the matter.
The giant white airship was last seen over Missouri and is expected to reach the US East Coast near the Carolinas over the weekend.
In another development, the US on Friday announced a second Chinese balloon to float over Latin America.
China, which has expressed regret over the incident, said on Saturday it had "never violated the territory and domain of any sovereign country."
In a statement, its State Department played down the cancellation of Blinken's visit and said neither side had formally announced such a plan.
It added that Beijing "would not accept any groundless conjecture or hype" and accused "some politicians and media in the United States" of using the incident "as a pretext to attack and smear China."
According to US officials, the balloon floated over Alaska and Canada before appearing over the US state of Montana, which includes a number of sensitive nuclear missile sites.