MUCH of the cash that keeps Kim Jong Il's bankrupt regime in business stems from the 600,000 ethnic Koreans in Japan. They have plenty of grievances with their host country and a lot of sympathy for the regime in Pyongyang. Many feel duty-bound to donate money for its upkeep. Japanese authorities have watched helplessly as the cash flowing from pachinko parlours (pinball arcades run largely by the Korean underworld) has also gushed offshore.

The sluice-gates are at last closing. In September the Japanese government approved measures to block the transfer of funds to North Korea. Banks had to report suspicious transactions and to demand proof of identity for cash transfers exceeding ¥100,000 ($840). Previously, sums up to ¥2m could be transferred anonymously as cash, even without an account in the bank concerned.

The government gave the banks three months to prepare for the extra workload and to alter their automated teller machines so they could not accept large sums of anonymous cash. On January 4th the new money-laundering measures came into effect.

Since its nuclear test last October, North Korea has been facing tighter international sanctions. For its part, Japan has banned North Korean vessels from its ports and tightened export controls. Any money or supplies reaching North Korea from Japan these days have to be carried by ethnic-Korean tourists. But with ferry connections between Japan and North Korea discontinued, Koreans wishing to make the pilgrimage to their ancestral home now have to charter flights via Beijing. This adds hugely to the cost, and deters many. On their return, they now have to brave immigration officials with new powers to deny re-entry to Japanese passport-holders who have visited North Korea.

No surprise that Mr Kim has been dishing out invitations to power-brokers in Japan's ruling Liberal Democratic Party (LDP) to visit. The only taker so far has been Taku Yamasaki, an out-of-favour former vice-president of the LDP, who failed to inform party bosses about his trip until he was already on his way. Judging from the outrage in the prime minister's office, Mr Yamasaki will be even more out of favour when he returns—provided, of course, the immigration officials let him back in.