A teen has been detained by Singapore authorities on suspicion of planning to set up an Islamic caliphate and undertake armed violence in support of ISIS.

Muhammad Irfan Danyal bin Mohamad Nor, an 18-year-old student, was convinced the terrorist group was legitimate after consuming extensive ISIS propaganda online, the Ministry of Home Affairs said in a statement Wednesday. He was arrested in December after authorities determined that he posed an “imminent security threat.”

Irfan allegedly planned to stab and kill “disbelievers” in dark alleys, carry out a mass-casualty attack against a military base and build a homemade explosive to bomb a grave site he deemed “un-Islamic,” the ministry said.

The teen planted a self-made flag inspired by Al-Qaeda on Singapore’s Coney Island on the city-state’s National Day last August, and intended to declare it an ISIS province, according to the statement. He is also suspected of making plans to travel overseas to commit violence there once he saved up enough money.

The case “highlights the appeal of ISIS’s violent ideology, sustained through its online propaganda efforts and network of global affiliates,” the ministry said. Irfan was first exposed to such content in 2020 when he came across YouTube videos by a foreign extremist preacher.

Irfan was arrested under the Internal Security Act, which allows for lengthy periods of preventive detention without trial. He is the third self-radicalized youth to be detained for planning to carry out attacks in Singapore in the past two years, the statement said.