WASHINGTON (Yonhap) -- A U.N. human rights resolution on North Korea could complicate Japan's efforts to resolve the issue of Pyongyang's past abductions of Japanese citizens, a U.S. expert said.

Japan was one of the main sponsors of the resolution that passed through the Third Committee of the U.N. General Assembly last week amid keen international attention due to its call for referring North Korea to the International Criminal Court for human rights violations.

The passage came as Japan and North Korea have worked together to resolve the abduction issue, with Pyongyang launching a reinvestigation into a dozen officially recognized Japanese abduction victims and other missing Japanese, and Tokyo lifting some sanctions on Pyongyang in return.

North Korea has reacted angrily to the resolution, threatening to conduct a nuclear test in protest and accusing the United States of orchestrating its passage in an attempt to topple the regime. It also threatened "the toughest counteraction" against Japan and other sponsors.

"This rhetorical flourish is not new, but interestingly the Kim regime threatened military retaliation rather than using the reinvestigation as leverage," said Sheila Smith, a senior fellow for Japan studies at the Council on Foreign Relations (CFR).

"Kim Jong-un's strategy may yet be to entice Japan into a separate deal, but the UN resolution certainly adds a new twist to an already opaque North Korean effort to bargain with Tokyo," she said in a report published on 38 North, a website run by the U.S. Korea Institute at the Johns Hopkins School of Advanced International Studies.

Noting that Japanese Prime Minister Shinzo Abe will be judged at home on his ability to bring Japanese citizens back from North Korea, the expert said that if Pyongyang proves yet again that it has no serious intent to engage in diplomatic negotiation, the domestic tolerance for continued Japanese government effort will diminish even further.