WASHINGTON, June 1. /TASS/. The White House said on Friday it had nothing new to say about media rumors of US President Donald Trump’s support for his Turkish counterpart’s proposal to set up a joint working group on the Russian-Turkish contract for S-400 missile systems.

"We have nothing new to announce at this time. We have been clear that obtaining the S-400 would create an unacceptable risk to U.S. technology, our pilots, and our aircraft. The United States has sent technical teams to Turkey more than once and hosted counterparts here to discuss the threat posed by the S-400. We continue robust discussions with our Turkish counterparts at all levels," said Garrett Marquis, a spokesman for the White House's National Security Council.

In a phone conversation on May 29, Turkish President Recep Tayyip Erdogan once again suggested to Trump to form a joint working group to resolve disagreements over Ankara's purchase of Russia's S-400 missile defense systems. Later, Turkey’s national news channel NTV reported that Trump was positive about the initiative. It is expected that the two presidents will also hold talks on the sidelines of the G20 summit.

The first reports about the talks between Russia and Turkey on the deliveries of S-400 air defense missile systems emerged in November 2016. Russia confirmed in September 2017 that the relevant contract had been signed. Turkish Defense Minister Akar earlier said that the deployment of S-400 surface-to-air missile systems would begin in October 2019. Rostec CEO Chemezov said in December 2017 that the S-400 deal was worth $2.5 billion.

The US has been vigorously trying to stonewall the S-400 deal. Earlier Washington warned Ankara that should the deal with Russia be implemented, the US would not supply its F-35 fighter-bombers to Turkey.

The S-400 Triumf is the most advanced long-range air defense missile system that went into service in Russia in 2007. It is designed to destroy aircraft, cruise and ballistic missiles, including medium-range missiles, and can also be used against ground installations. The S-400 can engage targets at a distance of 400 km and at an altitude of up to 30 km.