A recent survey indicated that about ten percent of the people (military and civilian) in the U.S. Department of Defense have some foreign language skills. Of these 247,000 linguistically gifted people, only 20,000 are talented, or needed, enough to receive special pay. This amounts to up to $12,000 a year for active duty troops, and $6,000 a year for reservists. The max rate is available to those with high skill levels in Arabic, Turkish (used in Central Asia), Farsi (Iranian), Chinese, Korean, Dari (Farsi dialect spoken in Afghanistan), Hindi (many dialects), Somali and Swahili (common language in East Africa). The minimum bonus is $3,600 a year. Skills are tested regularly to maintain qualification.
The Department of Defense has almost completed a detailed survey of language skills among all its personnel, and has found that 22,000 has some skill (from crude to fluent) in Arabic, Chinese, Farsi and Hindi. These languages are much in demand by the armed forces. The plan is now to encourage those who are less-than-fluent to improve their skills. Free training will be provided, with the prospect of those bonuses once greater proficiency is achieved.
Linguists are crucial for successful intelligence work, in peace as well as war. In particular, you want people who have security clearances, or who can get them. Department of Defense employees fit the bill here. Otherwise, you have to hire civilian linguists, who often do not have clearances, cannot get them, or are actually liable to act as spies for foreign nations.