SEOUL, South Korea (AP) — A 78-year-old South Korean man died hours after setting himself ablaze near the Japanese Embassy in Seoul today, police said, at a time of worsening tensions between Seoul and Tokyo.

The man, surnamed Kim, ignited a fire inside his car parked in front of the building where the Embassy is located. The man died later today while being treated at a Seoul hospital, police said.

Police said Kim had phoned an acquaintance earlier to say he planned to self-immolate to express his antipathy toward Japan.

Kim’s family told investigators that his father-in-law had been conscripted as a forced laborer when the Korean Peninsula was under Japan’s colonial rule from 1910-45, according to a police statement.

No suicide note was found. Police earlier said flammable materials were found in the car that Kim borrowed from an acquaintance Thursday.

Police said they’ll analyze possible evidence from Kim’s mobile phone and investigate people concerned to try to determine the exact motive for his action.

The man’s self-immolation comes with relations between Seoul and Tokyo at their worst in decades after Japan recently tightened export controls for some high-tech materials.