MBTs, in four separate batches of 250 units, with the MİTÜP Turkish National Tank Project. The tanks will be produced by the Turkish firm Otokar, and share some of the systems that are used in the K2 Black Panther main battle tank of South Korea. Turkey has signed an agreement with the US to buy fourteen CH-47F Chinook helicopters, for $400 million. Because of financial constraints, however, the Undersecretariat for the Defense Industry, or SSM, Turkey's procurement agency, later wanted to buy only six CH-47Fs, five for the Army and one for the Special Forces, leaving a decision on the remaining eight platforms for the future. Contract negotiations between the SSM, the U.S. government and Boeing were launched last year. The length of compulsory military service is six months for private and non-commissioned soldiers (the service term for reserve officers chosen among university or college graduates is 12 months). All male Turkish citizens over the age of 20 are required to undergo a one-month military training period, but they can obtain an exemption from the remaining five months of their mandatory service with a paid exemption option. Turkey has chosen a Chinese defence firm to co-produce a US$4 billion long-range air and missile defence system FD-2000, rejecting rival bids from Russian, US and European firms. The Turkish defence minister announced the decision to award the contract to China Precision Machinery Import and Export Corp (CPMIEC) in a statement on Thursday, September 26, 2013. NATO has said that missiles should be compatible. In 2017, Turkey has bought the anti-aircraft S-400 missile system from Russia. The TLF has seen frequent recent combat around and beyond its borders. It is fighting a conflict in south-eastern Turkey against the prolonged Kurdish PKK insurgency, and monitoring ISIS, Russian intervention in Syria, the Kurdish YPG, as well as multiple other elements, in Syria. It maintained a prolonged command of Regional Command Capital in ISAF. Thus the TLF has had extensive combat experience. Structure The structure of the Turkish Army has historically had two facets: operational and administrative. The operational chain consists of the field fighting formations, and the administrative the arms and service branches – infantry, armour, artillery etc. Operational organisation The army's 14 armoured brigades are the most powerful brigades in the restructured organisation; each includes 2 armoured, 2 mechanised infantry and 2 self-propelled artillery battalions. The 17 mechanised brigades each have 1 armoured, 2