Leaders of U.S. groups lobbying for the return of children abducted by a parent across international borders reacted with skepticism to Prime Minister Shinzo Abe's explanation to U.S. President Barack Obama that Japan is close to joining a convention to resolve such incidents.

"The fact that they are not even addressing current cases does not give me much confidence in Japan's sincerity on this issue," Paul Toland, coordinating director of Bring Abducted Children Home, said in an interview.

Toland's group lobbies on behalf of parents whose children have been abducted by an estranged spouse to Japan, which has yet to ratify the 1980 Hague Convention of the Civil Aspects of International Child Abduction. Toland has not seen his 10-year-old daughter since she was 1, after she was spirited away by her Japanese mother who has since died.