By Alex Jensen

SEOUL

 South Korea’s foreign ministry has moved to strengthen security at its missions in Japan, according to local media Saturday -- after a box containing feces was found in the parking lot of the South’s Consulate General in Yokohama.

An accompanying message signed by an anti-Korea group explained that it was an act of “revenge” for last month’s explosion in a restroom at Tokyo’s Yasukuni Shrine for war dead, according to Yonhap.

Although bomb specialists were initially deployed to the consulate general earlier Saturday, Yokohama police later confirmed that the foot-long package contained dried feces.

The mission also revealed that security footage from Friday afternoon showed a man throwing a box onto the premises.

A 27-year-old South Korean man surnamed Chon -- also spelled Jeon -- emerged as the main suspect following the Nov. 23 Yasukuni blast, which caused no casualties.

The shrine is a source of grievance in nations that suffered under Imperial Japan, including the South and China, because it honors Class-A war criminals among millions of war dead.

Nationalist groups and even mainstream conservative politicians in Japan have been accused of trying to whitewash history by failing to recognize the extent of Tokyo’s colonial era abuses.

Chon was detained upon his return to Japan Wednesday, having been spotted at the scene of the blast -- but South Korean airport officials denied that he was carrying more explosive materials, contrary to reports.

Seoul lodged a protest this week after being upset by Japanese media coverage, which failed to protect Chon’s identity.