TOKYO, Japan — Under normal circumstances it would be impossible to summon any sympathy for a man who snatches two young children as they walk to school with their mother.

But what if the “abductor” is the children’s father, and the mother, his former wife, herself the subject of an arrest warrant?

When Christopher Savoie, an American, went to these extraordinary lengths to regain custody of his children from his Japanese ex-wife last month, he not only landed himself in a police cell for more than two weeks, he also placed the spotlight firmly on Japan’s complicity in international parental child abduction — turning it from a minor irritant into a potential source of genuine tension between Washington and Tokyo.

Savoie was arrested after attempting to take his children, aged 9 and 6, to the U.S. consulate general in Fukuoka, southwestern Japan, in September.

The 38-year-old from Tennessee, and his former wife, Noriko, lived in Japan for several years before moving to the U.S. in 2008. When they divorced in the U.S. in January this year, Noriko was granted primary custody of the children.

Despite giving assurances that she would remain with the children in the U.S., in August she took them to Japan, without Savoie’s knowledge and in defiance of a court order. The U.S. authorities awarded Savoie full custody in Noriko’s absence and issued a warrant for her arrest on suspicion of “custodial interference.”

Yet Savoie has no legal right to see his children for as long as they remain in Japan, which refuses to sign the 1980 Hague Convention on International Child Abduction.

The treaty, with 81 signatories including every other member of the G7, states that a “child whose parents reside in different countries shall have the right to maintain on a regular basis … personal relations and direct contacts with both parents.”

Savoie’s is one of about 80 cases of international parental child abduction involving U.S. citizens, while France and Britain are dealing with 35 each.

The unofficial number is much higher, particularly when failed marriages between Japanese and people from other Asian countries are included. The Assembly for French Overseas Nationals for Japan estimates that 10,000 children with dual citizenship in Japan are prevented from seeing their foreign parent after separation or divorce.

Japanese courts habitually award custody of children to the mother. In many cases, they say they are simply trying to protect the rights of women fleeing abusive former husbands, a claim vigorously disputed by campaigners.

The country’s courts will be tested again later this week when Shane Clarke appeals in a custody battle with Japanese ex-wife.

The 39-year-old Briton has not seen his two young daughters since May 2008 after his ex-wife took them to Japan to visit their “ill” grandmother and never returned.

Though Britain’s media has taken an interest in his plight, Clarke says he has received little support from the authorities, despite a court order naming the U.K. as his children’s country of habitual residence.

“I have been writing repeatedly to more than a dozen government ministers, and not a single one has had the common decency to reply,” he told GlobalPost.

Legal precedent indicates that Clarke, who was denied custody at a hearing in Japan last year, will again return home without his daughters.

“We are talking about two British citizens, and no one will help me. The message our government is sending out to foreign nationals is that it’s perfectly all right for them to commit a crime on British soil, and as long as they leave the country quickly enough, they’ll get away scot-free.”

Left-alone parents in the U.S. have fared better. Chris Smith, a New Jersey congressman, recently urged the Japanese prime minister, Yukio Hatoyama, to use the Savoie arrest as a “catalyst” to end Japan’s tacit approval of international parental child abduction.

Smith has drawn up legislation that would enable the U.S. to “more aggressively” pursue the rights of American parents, including imposing sanctions against countries that habitually refuse to cooperate on international child abductions.

Pressure is also mounting in Japan, where the ambassadors of eight countries, including the U.S., have urged the justice minister, Keiko Chiba, to sign the Hague treaty.

The foreign minister, Katsuya Okada, indicated he would speed up a study into the agreement’s pros and cons, although ratifying it will require changes to domestic laws that could take years to implement.

Savoie, meanwhile, says he is struggling to come to terms with the possibility that he will not see his children again until they are adults.

“If loving my kids so much that I really want to be with them is a crime, then, well, I’m guilty,” he told CBS News after returning to the U.S. “I’m guilty of loving my kids.”