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1. British S.A.S

The United Kingdoms best special forces, these elite force take in an average number of 125 candidates each year but majority fail except for an average of 10 candidates that survive, the first three weeks of there training tests them on endurance and challenges them not only physical fitness but there mental stamina as well. Then are trained in the jungle to test there survival skills and after than they are trained in how to be questioned and how to questioned people for information.

2. Navy SEALs

The Navy SEALs are considered to be the best of the best, the United States most elite special forces they have, they training is considered to be brutal and they prepare you for mental and physical challenges. The initial training last more than a year and involve underwater demolition, parachute school, etc. After that it follows by an additional 16 months in which they specialize in training

3. Russian Spetsnaz

The Russian Spetsnaz are a Russian specialist unit that was first formed back in 1957 there are consider one of the hardest training and recruitment and some of there methods are considered to be illegal in the united states. They specialize in hand-to-hand combat, self-defense, they are taught to not crack under interrogation and how to interrogate

4. Shayetet 13

The Shayetet are a Israeli Navy Special Forces unit that, recruiting last about 20 months and is split into five stages and they are held twice a year. Six month of basic and advance infantry training, 4 weeks of combat diving, 3 months of diving and combat, after that there last stage latest about a year and is where they receive most of the dropouts in this stage and its the stage when they begin the more specialize and hard training.

5. Pakistan Special Service Group (SSG)

The SSG is the Pakistan special unit and considered to be there response team to serious situations, in order to join the SSG the officer must have at least two years of military experience. They must participate in a 9 month SSG course to view, their physical condition after that they enter a more advance course which latest about 25 weeks and are taught more hand on hand combat and infantry.

https://www.thetoptens.com/most-well-trained-special-forces/

https://www.navy.com/careers/navy-seal

http://www.eliteukforces.info/special-air-service/