MOSCOW, June 27. /TASS/. /TASS/. Turkish President Recep Tayyip Erdogan said on Thursday he believes US President Donald Trump knows why Ankara had decided to buy Russian S-400 missile systems.

"Mr. Trump knows Turkey's concerns, why we needed this system and how we came to this point very well," he said in an interview with Japan’s Nikkei Asian Review ahead of the Group of Twenty summit in Osaka.

He said talks with the US administration on that matter were underway. He also noted he hoped to speak about that with Trump during the Group of Twenty summit. Besides, in his words, Trump’s visit to Turkey is July was being looked at.

The Turkish president warned the United States that Ankara would turn to the international arbitration court if Washington refuses to implement the contract for F-35 fighter jets. "We have already paid them $1.25 billion for the F-35 project. If they do make such a wrong move, we will take it to the international arbitration court because we will want them to pay us back the money we have spent so far," he said.

When asked about Turkey’s response in case the United States imposed sanctions over the purchase of Russian S-400 systems, Erdogan said it was impossible to apply the Countering America's Adversaries Through Sanctions Act (CAATSA) to Turkey "because we took this step [of buying the S-400] before CAATSA came into effect."

Bloomberg said on June 19 the US administration was looking at possible sanctions against Turkey over its plans to buy Russian S-400 systems.

The media reported in November 2016 that talks were underway on possible sales of Russian S-400 systems to Turkey. The Russian side confirmed that the contract had been signed in September 2017. Turkish Defense Minister Hulusi Akar said back then that the deployment of S-400 systems would begin in October 2019.

The United States has been seeking to break down the deal. It has repeatedly warned Turkey that in case it buys the Russian missile systems it would not get F-35 fighter jets.

Russia’s S-400 Triumf (NATO reporting name: SA-21 Growler) is the latest long-range antiaircraft missile system that went into service in 2007. It is designed to destroy aircraft, cruise and ballistic missiles, including medium-range missiles, and surface targets. The system can hit aerodynamic targets at a range of up to 400 kilometers (249 miles) and tactical ballistic targets flying at a speed of 4.8 km/s (3 mi/s) at a distance of up to 60 kilometers (37 miles). Such targets include cruise missiles, tactical and strategic aircraft and ballistic missile warheads.

The system’s radars detect aerial targets at a distance of up to 600 kilometers (373 miles). The system’s 48N6E3 surface-to-air missiles can hit aerodynamic targets at altitudes of 10,000-27,000 meters and ballistic threats at altitudes of 2,000-25,000 meters.