"There could be more sanctions to follow but frankly what we’d really like is for the S-400 not to become operational," Pompeo told Bloomberg Television on Thursday.
Earlier in the day, Russia completed the first stage of shipments containing the S-400 air defence system’s components. Turkish President Recep Tayyip Erdogan has said the S-400 system would become fully operational for the country’s military by April 2020.
On Tuesday, top Democrats on the Senate Foreign Relations Committee in a letter to President Donald Trump called for sanctions on Turkey for acquiring the S-400 system. The lawmakers said that without a firm action by the United States its sanctions regime on Russia will suffer.
The White House said in a statement on July 17 that the purchase of the S-400 system had made it impossible to keep Turkey in the F-35 fighter jet program.
Last week, US Under Secretary of Defence for Acquisition Ellen Lord told reporters the Pentagon would unwind Turkey from the F-35 Joint Strike Fighter Program by March 2020 due to Ankara’s decision to purchase Russian S-400 defence systems. Lord also said the United States will spend up to $600 million in non-recurring engineering to shift the supply chain.
The Turkish Foreign Ministry called the US move a unilateral step that may bring irreparable damage to bilateral relations.
Russia and Turkey had signed an agreement for the delivery of four S-400 batteries in December 2017.
The United States and NATO member states criticized the agreement and expressed concerns over the S-400 system’s incompatibility with NATO's air and missile defence systems.