Police arrested an 18-year-old high school student from the city of Ichinomiya in Aichi Prefecture Tuesday over the alleged possession of high explosives, including a type used in overseas terror attacks.

The arrest stems from a discovery in the teen's possession approximately 31 grams of a powder containing triacetone triperoxide (TATP) and around 5 g of another powder containing hexamethylene triperoxide diamine (HMTD) at his home on Feb. 10. TATP is commonly used in terror attacks because it can be produced using readily accessible ingredients.

Investigators suspect the teen intended to use these explosives to cause harm to people or property.

In February, prefectural police acting on a tip-off searched the student's home and seized various chemicals, beakers, test tubes and other materials. The explosives, stored in plastic cases and small bottles, are believed to have been produced at his residence.

The investigation was triggered at the beginning of this year by a tip from a vendor outside the prefecture who sells fertilizer and other products, who reported a purchase of potassium nitrate — used to produce fertilizers and pesticides, but also fireworks and explosives — made under the boy's name.

The suspect has admitted to the charges.

Authorities are now investigating how the explosives were made — as well as the motive behind it — by analyzing the suspect's confiscated smartphone and other materials.

Translated by The Japan Times