The U.S. Department of Treasury imposed sanctions on Japan’s second largest yakuza crime syndicate, the Sumiyoshi-kai and its leaders today. The sanctions make it possible to freeze their U.S. assets and block their transactions with American corporations or other entities.

This is the second time the Obama administration has taken steps to disrupt the yakuza’s activities since it identified the Japanese mafia as a significant criminal organization.

The Sumiyoshi-Kai’s leader, Shigeo Nishiguchi, and the underboss Hareaki Fukuda, were added to the U.S. Treasury’s list of persons that are targeted for punitive financial measures.

The Sumiyoshi-kai is a designated organized crime group in Japan, regulated but not outlawed. It has offices, the members have business cards; fan magazines, comics, and books list the top executives and celebrate their exploits. The Sumiyoshi-kai, with close to 11,000 members, is based in Tokyo, with offices in the luxurious Ginza area and flashy Akasaka. The group’s moneymaking activities include real estate, construction, prostitution, temporary staffing, as well as the standard extortion, blackmail, and racketeering. In general, the Sumiyoshi-kai is less violent than other organized crime groups in Japan, and was active in offering emergency aid to Japanese citizens after the earthquake last year, even opening it’s office doors to stranded commuters, including foreigners.

In February of this year, the Obama administration imposed sanctions on the most prominent yakuza crime group, the Yamaguchi-gumi, as well as its top boss and his underboss.

Since the Yamaguchi-gumi merged with another Tokyo yakuza group, the Kokusui-kai, in November 2005, the Sumiyoshi-kai have rapidly been losing control of their turf in Tokyo. Factions of the Yamaguchi-gumi and the Sumiyoshi-kai have been waging minor gang wars over the last few years, recently culminating in shocking violence.

On Sept. 2, a group of 10 men wearing ski-masks burst into the Roppongi dance Club Flower at approximately 3:40 a.m. and assaulted four men and women sitting together in the VIP room, clubbing one to death and injuring the others, while 300 other people were present. The attack was believed to be a reprisal for an attack on Yamaguchi-gumi Kokusui-kai members in Roppongi on Dec. 14 of last year—an attack in which Sumiyoshi-kai members were allegedly involved.

The Sumiyoshi-kai also has been involved with Japan’s nuclear industry for several years, including receiving pay-offs from Tokyo Electric Power Company (TEPCO) in the past. Members of the Sumiyoshi-kai were arrested this year for their role in illegally providing labor to TEPCO. The Sumiyoshi-kai has been providing exploitable labor for Japan’s nuclear industry for more than a decade, including the Fukushima Nuclear Power Plant, both before and after the triple meltdown on March 11 last year. TEPCO, while primarily a Japan-based company, was involved with building a nuclear power plant in southern Texas.

The U.S. Treasury has not clarified whether the yakuza have any assets under U.S. jurisdiction or the results of the sanctions so far.

It should be noted that the U.S. government has still not designated the Triads, China’s mafia, as a significant criminal organization, according to U.S. government sources largely due to lack of cooperation from Hong Kong, Macau, and China. Also, the same sources say that Chinese lobbyists and some influential Las Vegas casino operators have pushed hard to keep the Triads off the list for fear that it would jeopardize their “cash-cow” casino operations in Macau.

The U.S. government is continuing to take a hard look at Japanese mafia groups and will probably designate one or two more within the next year.