Airplane manufacturer called incident outside Seattle hub "unacceptable," saying the guard would not be returning.

The planemaker finds itself in an increasingly untenable situation with its finances so dire that it can ill afford a drawn-out paralysis.

Boeing faces a potentially crippling strike in the Seattle region, depending on how 33,000 workers vote Thursday on a new contract that has angered many employees despite solid wage gains.

Boeing operates its defense business, which is in a separate unit from the company’s commercial plane segment, in the St. Louis area. There are about 15,000 Boeing workers here.