Turkey will not reverse its purchase of Russian S-400 missile defence systems and will take reciprocal steps after evaluating U.S. sanctions imposed over the acquisition, Foreign Minister Mevlut Cavusoglu said on Thursday.

Iran has begun construction on a site at its underground nuclear facility at Fordo amid tensions with the U.S. over its atomic program, according to satellite photos obtained by The Associated Press on Friday.

Turkey has evacuated seven military observation posts in northwest Syria, pulling back troops from territory controlled by the Syrian government to areas held by insurgents and Turkey-backed rebels, a Turkish source said on Friday.