If the Contracting Officer notifies the Contractor in writing that a strike or picketing: (a) is directed at the Contractor or subcontractor or any employee of either; and (b) impedes or threatens to impede access by any person to a DHS facility where the site of the work is located, the Contractor shall take all appropriate action to end such strike or picketing, including, if necessary, the filing of a charge of unfair labor practice with the National Labor Relations Board or the use of other available judicial or administrative remedies.