The first parts of a Russian S-400 missile defense system were delivered to NATO member Turkey on Friday, the Turkish defense ministry said, a development set to escalate tensions with the United States which has warned of sanctions over the deal.Turkey’s purchase of the Russian defense systems, which Washington says are not compatible with NATO’s defense network, is one of a series of issues which have put the allies at odds. The S-400 consignment was delivered to the Murted Air Base outside the capital Ankara, the ministry said in a statement which triggered a weakening in the Turkish lira to 5.712 against the dollar from 5.683 before the announcement.“The delivery of parts belonging to the system will continue in the coming days,” Turkey’s Defense Industry Directorate said separately. “Once the system is completely ready, it will begin to be used in a way determined by the relevant authorities.” A Russian Air Force AN-124 cargo plane had flown to Turkey early on Friday morning and was last tracked approaching Ankara, data from Flightradar24 website showed. Turkish broadcasters showed footage of the plane at the Murted Air Base.President Tayyip Erdogan said after meeting President Donald Trump at a G20 summit last month that the United States did not plan to impose sanctions on Ankara for buying the S-400s. Trump said Turkey had not been treated fairly but did not rule out sanctions. Washington says the S-400s could compromise its Lockheed Martin F-35 stealth fighter jets, an aircraft Turkey is helping to build and planning to buy.Turkey could face expulsion from the F-35 program under the sanctions. Erdogan has dismissed that possibility, but Washington has already started the process of removing Turkey from the program, halting training of Turkish pilots in the United States on the aircraft.Investors in Turkey have been concerned about the impact of potential US sanctions on an economy which fell into recession after a currency crisis last year.Ankara and Washington are also involved in disputes over strategy in Syria east of the Euphrates River, where the United States is allied with Kurdish forces that Turkey views as foes.The Murted base, northwest of Ankara, was formerly known as Akinci Air Base. It was used by putschist soldiers in the attempted coup of July 2016.