ISTANBUL \u2014 The first shipment of a Russian missile defense system has arrived in Turkey, the Turkish Defense Ministry said Friday, moving the country closer to possible U.S. sanctions and a new standoff with Washington.The S-400 consignment was delivered to the Murted Air Base outside the capital Ankara, the ministry said, in a statement."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."The U.S. has strongly urged NATO member Turkey to pull back from the deal with Russia \u2014 reportedly costing more than $2 billion \u2014 warning the country that it will face economic sanctions under the Countering America's Adversaries Through Sanctions Act if it goes ahead with the purchase. It has also said Turkey won't be allowed to participate in the program to produce high-tech F-35 fighter jets, an aircraft Turkey is helping to build and planning to buy.Russian President Vladimir Putin greets Turkish President Recep Tayyip Erdogan, left, on the sidelines of the G-20 leaders summit in Osaka, Japan.Yuri Kadobnov \/ AFP - Getty Images filePresident Tayyip Erdogan said after meeting President Donald Trump at a G-20 summit last month that the U.S. 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 has already started the process of removing Turkey from the F-35 program, halting training of Turkish pilots in the United States on the aircraft.U.S. officials have encouraged Turkey to buy the Patriot missile defense system instead of the S-400s. But Turkey says the offer does not meet its requirements, including possible future joint production.Turkey has refused to say where it intends to deploy the S-400. Turkish media reports have said it could take until October for the system to be fully operational.The deal with Russia \u2014 the first such deal between Russia and a NATO member \u2014 has also raised concerns that Turkey is drifting closer to Moscow's sphere of influence.