The airfield in Manas, which serves both US military aircraft and commercial flights, was "shut down" at about 8:00 pm local time in Kyrgyzstan (1400 GMT), said a US military official, who spoke on condition of anonymity.
Runways were tentatively due to be reopened at 8:00 am local time on Thursday, the official said.
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Opponents of President Kurmanbek Bakiyev seized control of Kyrgyzstan on Wednesday after a day of violence that saw at least 47 people killed in riots and clashes with police and ended with Bakiyev fleeing the capital of the strategic Central Asian state.
Base crucial to US war effort
The Manas base is crucial for the US war effort in Afghanistan amid a major troop buildup, with American aircraft ferrying soldiers, fuel and weapons to NATO-led forces fighting the Taliban.
"We'll work to alleviate that backlog (of flights) as soon as the airfield is reopened," the official said.
Kyrgyzstan last year threatened to close the base after receiving a promise of more than two billion dollars in aid and loans from Moscow, which many saw as a sign of Russian resentment over the US military presence.
Bishkek eventually agreed to keep the US base open after Washington more than tripled the rent paid to use Manas.
