Normally close allies Japan and Taiwan are locked in a dispute over fishing rights off a small rocky outcropping in the Pacific Ocean, a rare disagreement that is being cast as a final foreign policy test for Taiwan's outgoing president.
The Foreign Ministry in Taipei says Japan had no reason to detain a Taiwan-registered fishing boat Monday as it worked the Pacific Ocean southeast of Okinotori, an outcropping more than 1,075 miles south of Tokyo and 975 miles east of Taipei.
Okinotori has just about 100 square feet of rock above sea level -- no more than the size of a bedroom. Taiwan says Okinotori is a reef, not an island, and that Japan cannot claim an exclusive economic zone around it. Waters outside such zones are high seas, open to all.
But Japan calls Okinotori a true island, worthy of a 200-nautical-mile exclusive economic zone, and says the Taiwanese fishing boat was 150 nautical miles off the disputed outcropping.
Japan's coast guard detained the captain and nine crew members aboard the Tung Sheng Chi No. 16 and towed the fishing boat to Iwo Jima. The captain and crew were released Monday afternoon once the vessel's owner paid a $54,400 security deposit with the Taiwanese government's help.
The payment obligates those detained to show up for a court hearing in Japan, but does not mean Taiwan accepts Japan's maritime claim, Taiwan's Foreign Ministry said.
Taiwan has called for the two sides to negotiate the dispute according to international law or "settle it peacefully" with help from international organizations. Japan is refusing to hold talks, a spokesman for Tokyo's de facto embassy in Taipei said.
"Because we cannot accept Taiwan's position, we find it impossible to hold talks," said the spokesman, Shinichiro Misawa.
After being dogged for years by perceptions of a weak foreign policy, Taiwanese President Ma Ying-jeou, who has less than a month left in office, is trying to use the incident to show strength and to stand up for fishing interests loyal to his political party, analysts say.
Ma was elected in 2008 and must step down in May due to term limits. He made a name in office mostly for strengthening relations with China, expanding trade and tourism ties, but that effort met a public opinion backlash starting in 2014. China still hopes to unify with Taiwan despite opinion surveys in Taiwan that show a majority of people oppose that idea.
Taiwan's foreign minister summoned Japan's representative in Taipei for an hour Friday to lodge a protest over the fishing rights dispute. A few dozen fishermen had protested at the de facto Japanese embassy Wednesday, some hurling eggs.
Japan is keeping quiet because it believes that president-elect Tsai Ing-wen will be friendlier to Tokyo and that the two sides will be able to revisit matters once she assumes office in a few weeks, analysts say.
"Ma doesn't have anything to lose, only one month left, and this will be the last chance to show he's the protector of Taiwan's national dignity," said Alex Chiang, an international relations professor at National Chengchi University in Taipei. "I think Japan will hold on and talk to the new government because most people believe it will be more friendly to Japan."
This year, Ma also questioned the Philippines over its decision to challenge China in an international court in the Hague over claims in the South China Sea. A ruling in Manila's favor would also weaken Taiwan's claims in the area as well.
Ma's stance on territorial issues is one differentiating point for his Nationalist Party, or KMT, vis-à-vis Tsai's Democratic Progressive Party, said Lin Chong-pin, a retired strategic studies professor in Taiwan.
The Democratic Progressive Party has not indicated how Tsai's administration plans to defend Taiwan's maritime claims. The president-elect's party advised in a statement Friday that the government should "proactively communicate" with Japan to prevent new incidents.
"One of the reasons [for Ma to challenge Japan] is to distinguish the KMT from the Democratic Progressive Party, which is soft on Japan," Lin said.
Japan has previously shown a willingness to accommodate Taiwan on fishing issues.
In 2013, the two sides signed a deal giving Taiwanese fishing boats access to 1,400 square nautical miles near the Japan-controlled Senkaku Islands -- a jab at China, which also claims the islands them and calls them the Diaoyus.
Jennings is a special correspondent.