US Secretary of State Mike Pompeo delivers remarks during an event to release of 2019 Trafficking in Persons report at the State Department in Washington, US, June 20, 2019. Photo: REUTERS/Yuri Gripas.

US Secretary of State Mike Pompeo spoke with Turkey’s Foreign Minister on Saturday and expressed disappointment over the country’s acquisition of the Russian S-400 missile system, the US State Department said in a statement.

Washington had opposed Turkey’s purchase of the Russian missile defense system and threatened to impose sanctions. Since then, President Donald Trump has been unclear over whether his administration was planning such an action.

Several Republican and Democratic US lawmakers on Thursday pressed Trump to impose sanctions on Turkey over the purchase.