The move will anger the USA, which has warned that Turkey can not have both the S-400 anti-aircraft defence system and US F-35 fighter jets.
The first delivery of the Russian S-400 advanced long-range anti-aircraft missile system, also known as the SA-21 Growler, has arrived in Turkey.
Esper said he planned to speak to his Turkish counterpart later in the day, and that the Pentagon would have more to say about the dispute afterward.
Russian Federation began the delivery of an advanced missile defence system to Turkey it has been reported, a move likely to trigger USA sanctions against a North Atlantic Treaty Organisation ally and drive a wedge into the heart of the military alliance.
The first parts of the Russian missile system arrived on three planes at Ankara's Murted air base, Turkish media reported.
Through a law Congress passed in 2017 known as the Countering America's Adversaries Through Sanctions Act or CAATSA, any country that makes a "significant" deal with the Russian defense industry must come under US sanctions.
Washington believes the new Russian technology could compromise its F-35 stealth fighter jets, an aircraft Turkey is helping to build and to buy.
Beyond implying a crisis of solidarity in the North Atlantic Treaty Organisation alliance, the Russia-Turkey deal has been criticized by the USA and its allies because of the potential for sensitive information to be sent back to Russia by its advanced missile system.
Turkey maintains that it has fulfilled all of its financial obligations concerning the F-35 programme and can not be excluded from the project.
How has Turkey defended its decision to go forward with the purchase?
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The detention of USA consular staff in Turkey has also strained relations, along with disagreements over Iran, Venezuela and Middle East policy.
In a show of bipartisan agreement Friday afternoon, the Republican and Democratic leaders of the Senate Armed Services and Foreign Relations committees issued a joint statement, reinforcing the sense of the Senate that Turkey should suffer consequences for buying the Russian system that North Atlantic Treaty Organisation has long maintained puts its pilots at risk.
Turkish broadcasters showed footage of huge Russian Air Force AN-124 cargo planes offloading equipment at the air base.
The United States says the Russian military hardware is not compatible with North Atlantic Treaty Organisation systems and the acquisition may lead to Ankara's expulsion from an F-35 fighter jet program.
"The process will continue in the coming days", Anadolu Agency quotes him as saying.
Turkey has said it was forced to buy the S-400s because Washington refused to supply the American-made Patriot systems to Turkey. The Russian Ministry of Defense also shared a video showing the equipment being loaded onto the planes and then being offloaded in Ankara. "It's a political statement that the U.S. doesn't have a hegemony and control over North Atlantic Treaty Organisation members and particularly over Turkey", Ashraf said.
Turkey says the system is a strategic defence requirement, particularly to secure its southern borders with Syria and Iraq.
In an interview with the BBC this morning, Reed said that since Turkey "chose the S-400 so they will be suspended, indeed eliminated from the F-35 program". Earlier this month, U.S. Senator Lindsey Graham appeared to raise the bar for sanctions, saying they may be triggered only when the missile system is activated.
Turkey maintains that it has fulfilled all of its financial obligations concerning the F-35 program and can not be excluded from the project.