Inside a crowded convention center in South Korea last month, Japan’s new prime minister, Sanae Takaichi, beamed as she met China’s leader, Xi Jinping, for the first time. Mr. Xi smiled back, a rare display of warmth between the rival countries.

上个月，在韩国一个座无虚席的会展中心里，日本新任首相高市早苗与中国国家主席习近平首次会面，高市笑容满面。习近平也回以微笑——在这两个存在嫌隙的国家之间，这是难得一见的温暖场面。

Only a few weeks later, the relationship has come undone. Mr. Xi has unleashed a wave of reprisals against Japan over a recent comment by Ms. Takaichi about defending Taiwan, a self-governed democracy that Beijing considers part of its territory.

但仅仅几周之后，两国关系便急转直下。由于高市早苗近日关于保卫台湾的言论，习近平对日本采取了一系列报复措施。台湾是一个自治的民主政体，但北京视其为中国领土的一部分。

The dispute poses an early test for Ms. Takaichi, who took office late last month, the first woman to serve as prime minister in Japan’s history. As a lawmaker, she was a vocal critic of Mr. Xi, criticizing China’s militarization of the South China Sea and visiting Taiwan to show solidarity with its leaders.

对于上月底刚刚上任的日本首位女首相高市早苗而言，此次争端构成了一项早期考验。高市在担任议员时期是习近平的公开批评者，曾抨击中国在南海的军事化举动，也曾访问台湾以表达对其领导人的支持。

Now, with the crisis threatening to overwhelm her nascent administration, Ms. Takaichi’s task, analysts say, is to avoid an escalation while still projecting strength at home.

分析人士指出，如今这场危机有可能压倒她刚起步的政府。高市当前的任务是避免局势升级，同时还要在国内展现强硬姿态。

“Nobody expected that her tenure would begin with a full-blown row with China,” said Mireya Solís, director of the Center for Asia Policy Studies at the Brookings Institution in Washington. “The challenge now is how to de-escalate without caving to China, or appearing to back down in a way that would weaken her domestically.”

“没人想到她的任期会以一场与中国的全面争端开场，”位于华盛顿的布鲁金斯学会亚洲政策研究中心主任米雷娅·索利斯说。“现在的挑战是，如何在不向中国让步的情况下缓和局势，也不能表现得退缩，否则会削弱她在国内的支持。”

The flare-up shows no signs of easing. The Chinese government has urged its citizens not to visit Japan, potentially sapping a major source of tourism, and Beijing signaled this week that it might move to restrict imports of Japanese seafood. China also dispatched Coast Guard ships to patrol near islands that both countries claim and warned Chinese students in Japan about what it said were risks to their safety.

这场冲突毫无缓和迹象。中国政府已敦促公民不要赴日旅行，这可能削弱日本重要的旅游收入来源；北京本周还暗示可能限制日本海产品进口。中国还派遣海警船前往中日双方声称拥有主权的争议岛屿附近巡逻，并提醒在日本的中国留学生注意所谓安全风险。

More reprisals could still come; China has a record of economic coercion. During a dispute in 2010, China limited the export of critical minerals to Japan, including rare earth metals. Chinese state media urged boycotts of South Korean companies operating in mainland China in 2017 when punishing South Korea over its embrace of an American missile defense system.

报复措施可能尚不止于此。中国有实施经济胁迫的记录。在2010年的一场争端中，中国限制向日本出口包括稀土金属在内的重要矿物。2017年，北京方面因韩国部署美制反导系统而惩罚它，当时的中国官方媒体曾号召抵制在华经营的韩国企业。

“China has a playbook on how to apply pressure, and they’re going chapter by chapter,” Ms. Solís said. “The Chinese are not offering any off-ramp. The question is, what is the end game?”

“中国对如何施压有一套完整的剧本，他们正按部就班地执行，”索利斯说。“中国没有提供任何缓和途径。问题是：他们的最终目的是什么？”

The latest dispute began on Nov. 7, when Ms. Takaichi was fielding questions before the Diet, Japan’s Parliament. A lawmaker from a rival party asked her about potential “survival-threatening situations,” a classification that, under Japanese law, allows the deployment of the country’s military forces.

这场最新争端始于11月7日。当时高市早苗在国会接受质询。来自在野党的议员问她关于“存亡危机事态”的问题——根据日本法律，此类事态认定允许日本部署自卫队。

Ms. Takaichi said an attempt by China to blockade or seize Taiwan, which lies less than 70 miles from Japanese territory and sits astride shipping lanes vital for Japan’s economic survival, could qualify.

高市表示，如果中国试图封锁或夺取台湾，就可能构成“存亡危机事态”。台湾距离日本领土约110公里，且处于对日本经济命脉至关重要的航道上。

“If it involves the use of warships and the use of force, I believe that this could constitute an existential threat, no matter how you look at it,” she told Parliament.

“如果涉及军舰和武力的使用，不管从哪个角度看，我认为这都可能构成存亡危机，”她在国会说。

日本广岛县吴市海军基地，摄于今年。高市早苗表示，若中国试图夺取台湾，就可能构成“存亡危机事态”，从而有理由部署自卫队。

Previous Japanese prime ministers, including Shinzo Abe, Ms. Takaichi’s political mentor, had avoided specifying how they would respond if China moved against Taiwan.

包括高市的政治导师安倍晋三在内，此前的日本首相均避免具体说明若中国对台采取行动将作何反应。

Ms. Takaichi later said her remarks did not constitute a change in policy. But her comments provoked a furious response in China, with officials demanding a retraction.

高市后来表示，她的言论并未构成政策改变。但她的表态仍引发了中国的强烈反应，要求她撤回言论。

“Taiwan is China’s Taiwan,” Mao Ning, a spokeswoman for China’s foreign ministry, said at a news conference on Thursday. “Taiwan is none of Japan’s business.”

“台湾是中国的台湾，”中国外交部发言人毛宁周四在记者会上说。“台湾是否有事，根本不是日本的事。”

China and Japan have feuded for decades, largely because of the legacy of World War II, when the Japanese army committed atrocities, including the 1937 Nanjing Massacre, crimes for which Beijing believes Tokyo has never sufficiently apologized.

中日两国数十年来一直龃龉不断，主要源于二战历史遗留问题，包括日本军队在1937年南京大屠杀中犯下的暴行，北京认为东京从未就此做出充分的道歉。

Even before Ms. Takaichi’s remarks on Taiwan, there were signs that Mr. Xi’s government was eager to increase pressure on Tokyo. China has been fanning anti-Japanese sentiment this fall as it commemorates the 80th anniversary of the end of World War II.

甚至在高市发表有关台湾的言论之前，已有迹象显示习近平政府有意加大对日本的施压。今年秋天，在纪念二战结束80周年之际，中国一直在煽动反日情绪。

“China was primed to respond,” said Bonny Lin, the director of the China Power Project at the Center for Strategic and International Studies. “But I don’t think anyone quite predicted the extent of the escalation.”

“中国原本就准备好做出强烈回应，”战略与国际研究中心中国实力项目主任林洋说。“但恐怕没人预料到升级会到现在这种程度。”

When Ms. Takaichi met Mr. Xi in South Korea, for a summit of the Asia-Pacific Economic Cooperation, she raised issues including China’s movements in the South China Sea and human rights abuses.

在韩国参加亚太经合组织峰会期间，高市早苗在与习近平会面时提出了包括中国在南海的行动和人权问题等议题。

Ms. Takaichi, who is grappling with a variety of domestic challenges, seems eager to let the dispute pass. She has ignored calls by some in her party to deport a Chinese diplomat stationed in Japan who recently issued a violent threat against her on social media. After the initial storm over her remarks, she told lawmakers she would refrain from “making explicit statements on specific scenarios.”

在国内面临多重挑战的高市似乎急于平息这场争端。她无视了党内一些人士要求驱逐一名驻日中国外交官的呼声，这名外交官近期在社交媒体上对她发出暴力威胁。在最初的舆论风暴过后，她对议员表示，今后将避免对具体情境作出“明确陈述”。

But it could be a long time before tensions calm. Ms. Takaichi’s party, the Liberal Democratic Party, lacks the back channels it once had to the Chinese government. The L.D.P. recently had a falling out with Komeito, its main coalition partner, which had served as a conduit to China.

但紧张关系可能难以在短期内平息。高市所属的自民党已经失去了以往与中国政府沟通的渠道。自民党近期与其主要执政联盟伙伴公明党关系破裂，公明党过去一直是与中国沟通的纽带。

“The Chinese are digging in, and Takaichi is unwilling to retract,” Ms. Lin said. “In the short term, there is no obvious way out.”

“中方态度强硬，高市也不愿退让，”林洋说。“短期内看不到明显的出路。”