Russian S-400s in Turkey is a 'necessity': minister
He also said Turkey was obliged to take measures against "intensive attacks" from the Syrian border as it is a priority for Ankara to protect its borders.The call comes a day after Turkey received the first batch of Russia's S-400 missile defence system on Friday, sparking NATO "concern" and risking deepening tensions with the United States, which has repeatedly warned against the purchase.
A fourth Russian cargo plane delivered another shipment of the air defence equipment to Murted air base near Ankara on Saturday, Reuters reported.
Akar told US Defence Secretary Esper that Turkey's purchase of Russian S-400 missile systems does not mean a change in the country's strategic orientation, the Turkish defence ministry said in a statement.
The two men agreed a US delegation would visit Ankara next week to discuss the details.
NATO, which counts Turkey as one of its members, is "concerned about the potential consequences" of the purchase, an official told AFP.On Friday, Esper said Washington's stance had not changed.
The delivery is likely to escalate tensions with the US after Washington warned this week that there would be "real and negative" consequences if Ankara bought the Russian defence system.
Washington has threatened to remove Turkey from its F-35 fighter jet programme, giving Ankara until 31 July to cancel the S-400 purchase or have its pilots kicked off the training course and expelled from the US.
But Turkish President Recep Tayyip Erdogan said after meeting US counterpart Donald Trump last month that he was confident Ankara would not face sanctions for buying the Russian missile system.
Erdogan told Trump during their meeting on the margins of the G-20 meeting in Japan that former president Barack Obama did not allow Ankara to buy Patriot missiles - an equivalent of the S-400s.
Trump sounded convinced and said: "You can't do business that way. It's not good."
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