Ahmad Salman Abdul Rahim chose to leave his job at a Malaysian construction company to fight alongside jihadists in Syria for a reason he says is 1,400 years old: The Prophet Muhammad demands it.

Muhammad, the founder of Islam, once advised a companion to fight in the area that makes up modern-day Syria and predicted that Allah would send an “army of mujahideen” to the region, Ahmad said. He said he’s there to avenge Muslims tortured and killed by President Bashar al-Assad’s regime.

…“It is not IS per se that might pose a danger to the region but rather its extreme militant ideology as well as the skills, battleground experience and international networks that Southeast Asian jihadists got from Syria and Iraq,” said Navhat Nuraniyah, an associate research fellow at Singapore’s S. Rajaratnam School of International Studies who looks at terrorism and radicalization.

…“Jemaah Islamiyah was very much weakened after Bali but now you can see these groups are reviving because the Syrian and Iraq conflict has given them political oxygen,” said Rohan Gunaratna, head of the International Centre for Political Violence and Terrorism Research at Nanyang Technological University in Singapore. “Southeast Asians in Iraq and Syria, when they return they will bring new skills, new expertise, new motivations, new ideologies, new networks.”

…“The fight in Syria, or the so-called struggle in Syria, is the first tweeted ‘jihad,’” said Mohamed Bin Ali, vice chairman and counselor at the Religious Rehabilitation Group, a group of Islamic scholars and teachers in Singapore that counsels extremists detained by the government. “Many of those who have been influenced, not only in Singapore, but from across the globe, they are indoctrinated, influenced via the Internet.”