Announcement comes two years after withdrawal was agreed to and 12 years since US mission to fight IS began

The Pentagon announced on Wednesday that it has formally completed its withdrawal of US troops from Iraq, two years after the withdrawal was agreed to and 12 years since the US mission to fight the Islamic State started.

After the announcement, Iran and its allies celebrated the departure as a victory, while Iraqi security experts worry that the withdrawal could give the Islamic State and others a chance to recover.