North Korea uses remittances from overseas illegal activities -- including cash from organized crime networks in Japan -- to fund its weapons of mass destruction programs, a senior official of the U.S. State Department said Wednesday.

At a hearing of the House of Representatives International Relations Committee, John Bolton, undersecretary of state for arms control and international security, said the North has used three sources of hard currency earnings to buttress its weapons programs.

"One is the sale of weapons of mass destruction: the North Koreans are the largest sellers of ballistic missile technology to 'proliferant' countries in the world," he said.

"The second . . . is the sale of illegal drugs. And third is a combination of remittances from illegal and quasi-illegal activity outside the country from, basically, organized criminal networks in Japan and elsewhere."

Bolton said the U.S. has focused on all three categories to prevent North Korea's "dictatorship" from getting its hands on funds.

If the U.S. can deny North Korea access to this money, it would have "a substantial effect not only in reducing proliferation, outward proliferation from North Korea, we think it could have an effect on the North Korean regime as well," Bolton said.

"Cutting off those hard currency earnings will not have any impact on the wretched and really horrible lives lived by the 22 million North Koreans who live in poverty," he said. "That money didn't do the slightest thing to improve their existence."

The money has been used to support the North's WMD programs and the elite in North Korea, Bolton said.