DAMASCUS, March 23 (Xinhua) -- The U.S.-backed Syrian Democratic Forces (SDF) announced on Saturday the defeat of the Islamic State (IS) militant group in eastern Syria, the SDF spokesman said.

The town of Baghouz, the last IS redoubt in eastern Syria, has been fully liberated, announced Mustafa Bali.

He also sent congratulations to the world on the elimination of the so-called IS caliphate in Syria.

The victory ended the IS rule that once spanned a third of Iraq and Syria.

The SDF, with the help of the U.S.-led coalition, has been fighting the IS group in the eastern bank of the Euphrates River region since last September.

Late Friday night, the Syrian Observatory for Human Rights war monitor said the SDF and the U.S.-led coalition were targeting a cave where 200 IS fighters were positioned.

It's worth noting that thousands of civilians and IS militants have surrendered to the SDF since last December.

While the SDF were targeting the last IS fighters in Baghouz, the White House said the SDF forces had retaken the final sliver of the IS territory.

The IS emerged in Syria after the crisis began in 2011, after it was formed first in Iraq amid the U.S.-led invasion of the country.

Abu Bakr al-Baghdadi, the group's leader, broke ties with al-Qaeda and renamed his group "the Islamic State of Iraq and the Levant" in 2013.

In 2014, the extremist group captured Raqqa Province in Syria and declared establishment of a caliphate.

However, the claimed victory by the SDF doesn't mean the elimination of the IS militants from Syria, as they have sleeper cells which are still capable of fomenting chaos.