Foreign travel shall not be undertaken without the prior written approval of the contracting officer. As used in this clause, foreign travel means travel outside the Continental United States, as defined in the Federal Travel Regulation. Travel to non-foreign areas (including the States of Alaska and Hawaii, the Commonwealths of Puerto Rico, Guam and the Northern Mariana Islands and the territories and possessions of the United States) is considered “foreign travel” for the purposes of this clause.