Washington (CNN) Amid diplomatic tensions between the US and Turkey on a range of issues, the US State Department announced Tuesday that it approved the possible sale of a $3.5 billion Patriot missile system to Turkey.

The approval is an attempt by the US to get Turkey to give up its plans to purchase the Russian-made S-400 missile defense system. The proposed purchase has been a major impediment to closer US-Turkish relations amid fears the Russian system could allow Moscow to collect intelligence on American and NATO systems.

Turkey's pursuit of the S-400 has jeopardized its acquisition of the F-35 joint strike fighter, as members of Congress have attempted to block Ankara's receipt of the jet over concerns about the Russian system.

Kremlin spokesperson Dmitry Peskov said Wednesday that Moscow is moving ahead with agreements to sell the Russian-made S-400 missile-defense system to Turkey, calling the news of the US Patriot missile sale approval "unrelated."

'Nothing more, nothing less'

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