The Voice of America reported that on Tuesday Lindsey Graham, one of the 45 Republican senators who attended the Sanctions on Turkey meeting in the White House, called on President Trump on the matter to urge Turkish Foreign Minister Mevlut Cavusoglu to refrain from activating the S-400 missile systems to avoid US sanctions. 

The same source said Senator Graham called Minister Cavusoglu himself on Wednesday. 

Graham reportedly said he is among the group of senators who think sanctions are not necessary if the S-400 systems are not activated, and urged the minister to convince Turkey. Graham said, "If the system is activated we have no choice. The sanctions act is clear."

Graham added that the activation of S-400 systems will "lead to a dark path for the US relations with NATO ally Turkey".

Reuters reported that the Congress is cautious about sanctions, and the matter is not a priority for now. Western News agencies say sanctions against Turkey are not likely until September 9 when the Congress returns from holidays. 

US State Department Spokesperson Morgan Ortagus held a press briefing and said the US has started the process of removing Turkey from the F-35 program: “The steps taken to date are important. It is a serious step to impose sanctions against a NATO ally.”

Ortagus said the Countering America's Adversaries Through Sanctions Act (CAATSA) doesn’t stipulate a timeframe for the imposition of sanctions: “We continue to voice our concerns in meetings with the Turks. There is nothing new to announce regarding the sanctions today.”