A disruptive passenger was released Wednesday after military jets escorted a commercial jetliner bound for Hawaii back to the Portland airport, authorities said.
"At this time, there is no known terrorism link," the FBI said in a statement. It said it had turned the case over to federal prosecutors but it was not immediately known whether charges would be filed.
Calls to the U.S. attorney's office were not immediately returned Wednesday.
The man was identified only as a 56-year-old from Salem, Ore.
The jetliner was headed for Maui and turned back about 90 minutes into a flight of about five hours.
"The captain made a decision to return the plane to Portland due to a suspicious passenger who made threatening remarks and refused to store his carry-on bags," said Suzanne Trevino, spokeswoman for the Transportation Security Administration.
Authorities provided no details about the threats or the issue with the baggage.
The North American Aerospace Defense Command didn't know what kind of disruption the Hawaiian Airlines flight crew was dealing with, spokesman John Cornelio said, so two F-15 fighters were scrambled as a precaution.
"Based on the information we had, we decided it was prudent to launch," he said.
He said the decision was NORAD's, not that of the Federal Aviation Administration.
The fighters came from the 142nd Fighter Wing of the Oregon Air National Guard, headquartered at the airport, said Gov. Ted Kulongoski.
The decision came amid heightened concern about airline security and allegiations that a Nigerian man tried to blow up a Detroit-bound Northwest Airlines plane on Christmas Day.
"In this day and age, any possible threat is taken very seriously, and today was a good example of that," said Martha Richmond, spokeswoman for the Port of Portland, which operates the airport.
The plane carried 231 passengers and a crew of 10, said Keoni Wagner of Hawaiian Airlines. The Boeing 767 was refueled in Portland and took off again for Hawaii, Wagner said.
The man left the plane with a companion, who also was questioned and released without charges, the FBI said.