Uyghur Islamic State fighters have purportedly released a video where they threaten to make “blood flow” in Chinese rivers, Reuters reported about the unauthenticated footage on Thursday. The video shows the fighters purportedly training for combat.

“In retaliation for the tears that flow from the eyes of the oppressed, we will make your blood flow in rivers, by the will of God!” one of the fighters is quoted as saying. Another person quoted in the 30-minute-long video allegedly said, “Today, we are fighting with infidels across the world! I’m telling you this: Come and live here! Stay strong. We will certainly plant our flag over America, China, Russia, and all the infidels of the world,” Reuters reported.

While Chinese Foreign Ministry spokesperson Geng Shuang said he had not seen the video, which was released by the United States-based SITE intelligence group, he said his country would participate in the international “crackdown on terrorism”. SITE monitors militant groups on the internet.

The extremist group had claimed responsibility for the killing of a Chinese hostage in 2015. Beijing is reportedly concerned about people leaving the troubled region to join the militant group in Syria and Iraq.

The Uyghurs, predominantly followers of Islam, consider Xinjiang their home. The region was turned into a Chinese province in 1884 under the Qing dynasty. Several reports have emerged about unrest in the region. However, Beijing has continuously denied accusations of imposing repressive policies in the region.