The United States has formally made an offer to Turkey for the sale of multibillion dollar Patriot air defense systems, the Anadolu Agency has reported, in a bid to increase its pressure on the latter’s purchase of Russian-made S-400 systems.

The Agency, citing officials, informed that a U.S. delegation is holding talks with their counterparts at the Defense Industry, Foreign Ministry and Defense Ministry. It said the U.S. delegation submitted the offer for the sale of Patriots to Turkey but did not give details on the offer.

The move comes after the U.S. State Department approved on Dec. 18 a possible foreign military sale of the Patriot air and missile defense system to Turkey for an estimated total of $3.5 billion.

According to the Defense Security Cooperation Agency, the State Department approved the sale of 80 Patriot MIM-104E Guidance Enhanced Missiles (GEM-T) missiles, 60 PAC-3 Missile Segment Enhancement (MSE) missiles and associated equipment.

It also had notified the U.S. Congress on the sale.

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