Israeli Defense Forces
The Israeli Defense Forces comprise all the armed services of the state of Israel; the country uses a unified model such that there are no naval or air force ranks or titles.
While the IDF is one of the most powerful militaries in the world, it has an unusually low rank structure. There is a single lieutenant general who is Chief of Staff of the Israeli Defense Forces, currently Gabi Ashkenazi. Many of the Chiefs of Staff have entered politics after retirement, and a number of the Prime Ministers of Israel have formerly been Chief of Staff.
18 years of age for compulsory (Jews, Druzes) and voluntary (Christians, Muslims, Circassians) military service; both sexes are obligated to military service; conscript service obligation - 36 months for enlisted men, 21 months for enlisted women, 48 months for officers; reserve obligation to age 41-51 (men), 24 (women) (2008) 
The IDF is very much a reserve-oriented military, with fairly small standing forces but the ability to mobilize large reserves within 48 hours. It is part of a broader national security structure, including a very capable military manufacturing sector.
Israel has used both preemptive attack and limited preventive war. Israeli air operations at the start of the 1967 Arab-Israeli War is taught in staff colleges worldwide as an example of preemption; the Israeli air force struck first, at Egyptian and Syrian airfields with aircraft clearly being readied for attack. Preventive actions have been more controversial and aimed at longer-range weapons of mass destruction threats, such as the Raid on Osirak, an Iraqi nuclear reactor under construction.
The main operational unit is the brigade.