A 49-year-old man named Atsunobu Usuda reportedly threw several firebombs at the headquarters of Japan’s ruling Liberal Democratic Party (LDP) in the Nagatacho district of Tokyo’s Chiyoda Ward, and rammed a van into a barricade at the nearby Prime Minister’s office on Saturday. According to local media, he threw five of what appeared to be Molotov cocktails in front of the main gate of the office and burned his minivan. No injury was reported immediately, but the Metropolitan Police Department later said that three riot officers sustained minor throat injuries, and a police vehicle was partially burned. A senior police officer who rushed to the scene was also reportedly thrown what appeared to be a smoke candle.

Usuda was arrested at the scene on suspicion of obstructing the performance of official duties. A large number of plastic containers filled with gasoline were found in the van. He did not resist the arrest but has remained silent since according to local media. Investigations were carried out to find out his motive. On the night of the incident, the police searched his home.

Usuda is from Kawaguchi in Saitama Prefecture. According to Usuda’s father, Usuda has been actively involved in the anti-nuclear energy movement in Japan, but that may not be linked to the attack. He also said Usuda had expressed dissatisfaction with the country’s election deposit system, which requires election candidates to pay a ¥3 million (USD 20,062) deposit that is refundable only if the candidate receives 10 percent or more of the vote.

The election deposit was first introduced in Japan in 1925 as part of an election law to counter-balance the increasing power of the working class. In case of a candidate’s failure to win the required vote in the election, the deposit may revert to the National Treasury or local authority under Article 93 of the Public Offices Election Law.

The attack took place amid the 12-day official campaign period of Prime Minister Shigeru Ishiba, who also serves as LDP president. According to local media, Ishiba planned to proceed with election campaign activities by taking all possible measures to ensure citizens’ safety and said in Satsumasendai in Kagoshima Prefecture, “Democracy must never succumb to violence.” LDP secretary general Hiroshi Moriyama also said the party will continue campaigning as scheduled, according to local media.