Iran-backed militia group Kataib Hezbollah said earlier on Tuesday that it would release Shelly Kittleson, who was taken on 31 March, on the condition that she leave Iraq immediately, BBC reported. 

Rubio said the release "reflects the Trump Administration's steadfast commitment to the safety and security of American citizens, no matter where they are in the world".

He thanked Iraqi officials for help securing her release and said the US is now "working to support her safe departure from Iraq".