WASHINGTON - The United States on Tuesday slapped a $3 million bounty on a former Tajik special operations commander who received American training but later defected to the Islamic State extremist group.

Gulmorod Khalimov, now 41, is a former colonel in Tajikistan's interior ministry police special operations unit and a trained sniper. Last year he declared allegiance to the IS group.

According to US officials, between 2003 and 2014 Khalimov attended five training courses in the United States and Tajikistan paid for by a US State Department anti-terrorism program.

In May 2015, he appeared in a video distributed online, bearded and in a black head scarf, bearing a sniper rifle and vowing to bring "jihad" to Russia, Tajikistan and the United States.

It was not clear where the video was shot but the footage includes a palm tree and reports have suggested that he travelled to eastern Syria, heart of the so-called IS "caliphate."

The United States designated Khalimov a "global terrorist" in September last year and on Tuesday added his name and a $3 million bounty to its "Rewards for Justice" program.

The State Department described him as a "key leader" of the Islamic State and as a recruiter for the militant group, which has seized cities in Syria and Iraq while seeking to inspire attacks worldwide.