I took Russian in high school during the 1960s. The teacher's salary was paid for by the government because not too many kids took Russian.
If the government wants schools to teach Arabic, the government needs to pay for the teachers because not enough kids will sign up for Arabic to make it cost-effective for the school.
High school is already late for learning a second language. Once you hit puberty, your brain begins to "lock-in", basically hardwiring the learning process. Adults who speak two languages can learn a third or fourth without nearly the same difficulty as a person who didn't learn any foreign language until after puberty.
I know the "English Only" types are gonna complain about this, but they have done more damage to American education and our ability to compete in the global marketplace (let alone conduct a reasonable foreign policy) than anyone else.
The government could attach a substantial financial premium on a student's gaining proficiency in the needed languages. The language training needs to start young. For instance, any kid who can pass an advanced fourth year level of written and oral Arabic by, for instance, 10th grade, would receive $40,000 or most of his college education paid, sort of like an ROTC arrangment, but in this case earlier on in the game, since languages need to be learned early. The student would owe the government a certain number of years of paid translation work - some even after high school and before college - using these language skills.