Turkey will buy two batteries of S-400 surface-to-air missile systems from Russia in order to fulfil the country's urgent requirement, Daily Sabah learned from security sources. The procurement agreement will likely be concluded when the Russian and Turkish finance ministers complete the loan agreement, the sources also indicated.Turkey and Russia have engaged in ongoing talks regarding Turkey's cooperation with Russia in the defense sector since the Russian-Turkish rapprochement in August 2016. However, the discussions have gained new momentum in recent weeks. Russian President Vladimir Putin's spokesperson Dmitry Peskov announced on March 15 that President Recep Tayyip Erdoğan and Putin had discussed this issue during Erdoğan's recent visit to Moscow on March 10, adding that both leaders were interested in the missile sale. Commenting on this issue, Turkish Defense Minister Fikri Işık said on March 16 that, "Progress is being made in the discussions," while adding that procurement talks have not yet been finalized. Officials for the Russian state corporation Rostec, which produces the S-400 systems, also confirmed that Ankara is ready to buy S-400 missile systems with a Russian loan, saying: "Turkey is expressing that it wishes to receive a loan. As soon as an agreement is signed and a decision is made on the amount of the loan, then we will sign a contract for the supply, including the S-400,'' Rostec CEO Sergey Chemezov said on March 14.The S-400 was developed as an upgraded version of the S-300 series of surface-to-air missile systems. The system entered service in April 2007 and the first S-400 was deployed in combat in August 2007. According to sources within the defense industry, a regular S-400 battalion consists of at least eight launchers with 32 missiles and a mobile command post. The system can engage all types of aerial targets, including aircraft, unmanned aerial vehicles (UAV) and ballistic and cruise missiles within the range of 400 kilometers (249 miles), at an altitude of up to 30 kilometers. The S-400 systems are capable of firing three types of missiles to create a layered defense, and the system can be deployed within five minutes, while simultaneously engaging 36 targets.As a N.A.T.O.-member, Turkey's procurement of the Russian S-400 system has raised concerns regarding the compatibility and integration of these weapons into the N.A.T.O. infrastructure. Minister Işık clarified last week that Turkey will use the Russian systems without integration, noting: ''Russia's S-400 missile systems will not be integrated into the N.A.T.O. system.''Minister Işık also said the Russian missile system will be used to fulfill Turkey's immediate requirement, while stressing that the uncompromising attitude of N.A.T.O.-member countries compelled Turkey to purchasing Russia's S-400 missile defense system. "We underwent negotiations to purchase N.A.T.O.-produced missile systems, but we could not get a reasonable offer in terms of price and technology transfer. Thus, our negotiations with the Russians have intensified," Minister Işık said on March 15.Meanwhile, Turkey's efforts to develop its indigenous long-range air missile defense system will continue, even after the procurement of Russian S-400s. ''We [Turkey] have already developed the short-range ballistic missile Hisar and are currently working on the mid-range Hisar project. Developments for our own long-range defense system are currently ongoing and we will be able to produce these systems within five to seven years,'' he said.The S-400 missiles are the new generation of Russian missile systems and Russia has only sold the system to China and India thus far. Last year, both China and India signed an intergovernmental agreement for the procurement of four regiments of Russian-made S-400s. Turkey will be the first N.A.T.O.-member country to purchase the system.