Tests on suspect liquids that led to the evacuation of an airport terminal in Huntington, West Virginia, have shown no explosives, officials say.
About 100 passengers were evacuated
The airport alert came after earlier explosives tests on two containers in a woman's luggage were positive.
The containers were seen in the woman's hand luggage and subjected to swab tests and sniffer dog examinations.
The woman has been cleared to travel, and the liquids are being taken to an FBI lab in Washington for more tests.
The alert at the small airport at Huntington began when a security screener reacted to material stored in the two containers.
The containers were moved to a remote area by robot for further tests, airport officials said.
The female passenger was detained and questioned for a time by FBI officials.
Officials say the woman is of Pakistani origin and was travelling on a one-way ticket to Charlotte, North Carolina.
Tri-State Airport director Larry Salyers said he was told the woman was a 28-year-old who had moved to Huntington from Jackson, Michigan.
The woman has now been cleared to travel as early as Friday morning, the BBC's Nick Miles reports from the Tri-State airport.
About 100 passengers were affected by the evacuation, airport officials say.
Local reporter Bob Aaron told the BBC that security at the small regional airport was not very sophisticated, relying on a few security screeners.
The incident comes a week after UK intelligence officers say they foiled a plot to blow up planes using liquid explosives.
This is the second security alert at US airports in as many days.
On Wednesday a United Airlines passenger jet flying from London to Washington was diverted and escorted to Boston after an on-board disturbance.