A nine-member Russian team will visit Turkey on June 27-28 for the first implementation of S-400 missile systems Ankara purchased from Moscow, Habertürk news site reported on Monday.

According to Çetiner Çetin, a reporter of Habertürk, Turkish and Russian security experts completed the scheduling of the delivery of Russian missile systems last week. The uploading of software has also been completed for two S-400 batteries, Habertürk said without identifying its sources.

Citing Russian diplomatic sources, Habertürk said Moscow wanted to make the delivery as soon as possible due to Washington’s increased pressure on Ankara over S-400 purchase.

The Acting U.S. Secretary of Defense Patrick Shanahan sent a letter to Turkish Defence Minister Hulusi Akar on Thursday detailing how Turkey’s participation in the F-35 program will be all but suspended as of July 31, unless Turkey withdraws from its planned purchase of Russian defence systems.

There is also a bipartisan support in the U.S. Congress for halting the delivery of the F-35 stealth fighter jets to Turkey, if Ankara goes ahead with plans to acquire S-400s.

İsmail Demir, the head of the main Turkish state body dealing with arms procurement and production, said on Monday that Ankara had responded Washington latest offer for U.S. Patriot batteries.

In order to avoid a possible suspension in the delivery, Russians wants to complete the installment of first S-400 missile system by July 15, Habertürk said.

Since Turkey agreed to pay a reported $2.5 billion for S-400s in 2017, there has been speculations on where the missile systems will be installed.

Bloomberg reported last month that Turkey is considering deploying Russian defence systems on its southern coast in an effort to boost its military capability in the Eastern Mediterranean amid heightened tensions over natural gas resources.

According to Habertürk, the S-400s will be placed on Turkey’s southeastern and Mediterranean borders.

Habertürk said Ankara might back down from acquiring Russian systems, if depending on Moscow’s policy on Kurdish-held enclaves in northern Syria. Turkey sees the Kurdish People’s Protection Units (YPG) as an extension of the outlawed Kurdistan Workers Party (PKK) and plans to establish a safe zone in norther Syria along the Turkish border to clear the area off the YPG.

If the U.S. President Donald Trump approves the establishment of a joint working committee Turkey proposed to discuss compatibility of S-400 batteries with NATO systems, Ankara will have a stronger hand against Moscow, Habertürk said.

But Demir said on Monday that the United States had not acted yet on forming a joint technical committee.

Trump and his Turkish counterpart Recep Tayyip Erdoğan are expected to meet on the sidelines of the G-20 summit to be held in Osaka, Japan, on June 28-29.