CIA offering hiring bonuses of up to $35,000 for those fluent in critical languages...the easiest one of those is Persian/Farsi

This is how you write "Mr. Ahmadinejad, are you our president or the president of Palestine?" in Persian. Grammatically it's a walk in the park compared to other languages, and written literally means "Mr-Ahmadinejad-you-president-of-we-you are-or-Palestine?"

No surprise, the CIA is still very short on new staff that speak so-called "mission critical" languages and is offering hiring bonuses of up to $35,000 for those that speak them.

So which languages are these? I believe there are a few more other than these, but the languages given in the article are:

Arabic, Chinese, Dari, Korean, Pashtu, Persian, Russian and Urdu.

The easiest language out of the above for your average English-language speaker with perhaps some background in Western European languages (Spanish, French, German, Italian, etc.) is Persian, and Dari is also a variant of Persian so they're not really separate languages. I've written before in detail on why Persian is an easier language to learn than even Western European languages, but here's a comparison of some of the aspects of the above languages with those of Persian to show why this is so.

• Arabic: HUGE regional variation, so learning Arabic usually means learning standard Arabic along with a regional variant, almost as much work as learning two languages instead of just one. Three cases, two genders, difficult plurals, different script, has a ton of consonants that English doesn't have, verb conjugation takes quite a while to learn.
• Chinese: Extremely simple grammar is a plus here. Besides that though it requires learning tones as well as a few thousand characters. Chinese is a language that just takes a lot of time and practice as you learn character after character and word after word, seemingly ad infinitum.
• Korean: Korean is tough to explain. Grammatically it's kind of like a condensed form of Japanese. The script is quite easy as Korean doesn't really use Chinese characters anymore, but to really understand the language you still need to put some time into learning the role they play in the language. Korean can be learned but it can be very tricky and seemingly counter-intuitive for those coming from a Western European linguistic background, with subjects often completely omitted, varying levels of politeness, and some doubled consonants that students often just can't figure out (like 자다 - jada, to sleep and 짜다 - jjada, to wring).
• Pashtu: An Iranian language and thus somewhat related to Persian, but is both used by less people (which makes it more difficult to find places to use it) and is also more grammatically complex. Has two genders, cases, and many irregular verbs, and also uses the Arabic script.
• Urdu: Urdu also uses the Arabic script, and has two genders and three cases, declined adjectives, and lots of fun in having to conjugate verbs by gender as well. One advantage is that a lot of people use the language (linguistically it's a variant of Hindustani, which includes Hindi), somewhere from 500 million to one billion.
  
• Russian: Russian is a very widespread language so it's very easy to find places to use it, and the relatively large amount of similar vocabulary (compared to the others) is also a plus. It's written in a different script as with the others above, but luckily it resembles the English alphabet quite a bit and is used in mostly the same way. However, the grammar is quite complex with three genders and six cases, extremely long words, and lots of exceptions. Just to say the word "this" for example you need to know the following forms:

	masculine	neuter	feminine	plural
Nominative	э́тот	это	э́та	э́ти
Genitive	э́того	э́того	э́той	э́тих
Dative	э́тому	э́тому	э́той	э́тим
Accusative	N or G	э́то	э́ту	N or G
Instrumental	э́тим	э́тим	э́той	э́тими
Prepositional	об э́том	об э́том	об э́той	об э́тих

• Finally, Persian. As written above there is a much more detailed post on what makes Persian much easier to learn than you might expect, but here's a simple overview: Persian is written in the Perso-Arabic script which naturally must be mastered, but after that it's a breeze compared to the other languages above. No grammatical gender, no declined adjectives, no cases, no articles, plurals are easy, and verbs are extremely simple. The only irregularity encountered in Persian verbs are some verbs that have an irregular present stem, so for these you just have to remember what the irregular stem is and then you conjugate as usual. One quick example of how much easier it is to pick up: see all the forms for the word "this" in Russian above? In Persian there's one: een (این). Done! Een gol - this flower. Een golhâ - these flowers. Een keshvar - this country. Een keshvarhâ - these countries.
  

This is not to say that Persian is just something you can pick up in an afternoon, however. It takes time (that means years) just as any other language does, and there is naturally slang and colloquial usage that needs to be mastered in addition to a formal standard. However, for someone just starting university that wants to get involved in intelligence or foreign relations and is intimidated by the list of languages above, think about picking up Persian. There's no reason a reasonably motivated student shouldn't be able to become completely fluent in the language after four years studying it at university. The other languages on the list...hard to say.