Bahrun Naim, an Indonesian militant fighting for the Islamic State in Iraq and Syria, used online financial services to fund terrorist activities in his home country.

The information comes from PPATK, an Indonesian agency against money-laundering, which claimed that Naim transferred PayPal and bitcoin funds to comrades in Java.

Naim is believed to be the mastermind behind the Jakarta attacks in January 2016. As per CNN, the former blogger already spent time behind bars in the past for illegal possession of ammunition. His blog contained ISIS teachings, DIY weaponry and anti-surveillance tips, among others.

Speaking to reporters, PPATK chairman Kiagus Ahmad Badaruddin announced that 25 cases of fraudulent transactions linked to terrorism were detected last year. He explained (via The Straits Times):

“Such fund transfers are more difficult to detect as they are not within the conventional banking system. We can detect them only when the end user finally encashes them through the banking system.”

Previously, PPATK reported that over 10 billion rupiah ($750,000) was transferred to Indonesia in 2014 and 2015. Ivan Yustiavandana, the agency’s director for examination and research, said:

“Today, we are talking about PayPal, bitcoin. Two to three years from now, we may talk about other means, new ways. The more sophisticated we are at getting them, the more they will try to look for new ways.”