Taiwan has grown accustomed to a near daily drumbeat of Chinese military planes flying close by, part of Beijing’s campaign to pressure the island it claims as its own. But lately, Taiwan has been facing an unexpected puzzle: Where have the planes gone?

台湾早已习惯了几乎每天都会响起的中国军机逼近的隆隆战鼓，这是北京对这个它声称拥有主权的岛屿施压行动的一部分。但最近，台湾面对着一个意想不到的谜团：那些飞机都去哪儿了？

For 12 of the past 13 days, no Chinese military flights were recorded near Taiwan. The sole exception was Sunday when two planes were seen approaching the island, according to daily data released by Taiwan’s Ministry of National Defense.

根据台湾国防部发布的每日数据，在过去的13天里，有12天未录得中国军机在台湾附近飞行。唯一的例外是周日，当时发现有两架飞机接近该岛。

“It is such a stark change from established behavior,” Ben Lewis, the founder of PLATracker, a website that collates the data from the Taiwanese defense ministry.

“这与长期以来的行为模式相比，是一个极其显著的变化，”汇总台湾国防部数据的网站PLATracker创始人本·刘易斯表示。

“This gap in activity is the longest we have seen since 2021,” Mr. Lewis said. That year, there was a three-week stretch that saw only five flights in total, and part of that time coincided with a tropical storm that churned around Taiwan. This time, the weather has been stable.

“这段活动真空期是自2021年以来我们见过的最长的一次，”刘易斯说。那一年曾有过一段持续三周的时间，总共只有五架次飞行，且其中一部分时间正值热带风暴在台湾周边肆虐。而这一次，天气状况一直很稳定。

Lulls in the number of People’s Liberation Army military flights are not new, including during China’s weeklong annual legislative session, which ends on Thursday. But in the past, there was still usually a smattering of flights at that time of year, according to the PLATracker. The fall was all the more striking against the buildup of Chinese military flights over recent years, Mr. Lewis said. Taiwan recorded about 10 Chinese military flights a day on average last year, and on some days the number went up to dozens.

解放军军机飞行数量的间歇性减少并非新鲜事，包括在中国为期一周的年度立法会议期间——该会议将于周四结束。但根据PLATracker的数据，往年这段时间通常仍会有零星的飞行。刘易斯表示，考虑到近年来中国军机活动规模的持续扩大，此次的下降显得尤为突兀。去年，台湾平均每天录得约10架次中国军机，有时一天甚至高达数十架次。

周一，出席中国全国人大年度会议的军队代表。

Analysts have offered several possible explanations, including that China may be setting the stage for President Trump’s planned summit with President Xi Jinping. China may also be trying to conserve fuel as oil prices rise because of the U.S.-Israeli war against Iran.

分析人士提出了几种可能的解释，其中包括中国可能正在为习近平主席与特朗普总统计划中的峰会做铺垫。此外，由于美以对伊朗开战导致油价上涨，中国也可能正试图节省燃料。

Many experts pushed back on speculation that Beijing is deliberately reducing tensions as a prelude to military action.

许多专家反驳了有关北京正刻意缓解紧张局势，作为军事行动前奏的猜测。

China’s Ministry of National Defense has not commented on the falloff. Taiwan’s defense minister, Wellington Koo, cautioned last week against reading the decline as a Chinese retreat from military threats against Taiwan.

中国国防部尚未就此次活动减少置评。台湾国防部长顾立雄上周发出提醒，告诫不要将这种减少解读为中国放弃对台军事威胁。

“We can’t simply look at whether the fighter aircraft are coming,” Mr. Koo told reporters in Taipei. “We need to look at a range of indicators.”

“我们不能只看攻机有没有来这个状况，”顾立雄在台北告诉记者，“我们还是要看各项的征候。”

Notably, the Chinese navy has not pulled back.

值得注意的是，中国海军并没有减少活动。

“We haven’t seen a comparable decrease in the reported number of P.L.A. naval vessels around Taiwan,” said Brian Hart, an expert in Washington, referring to the People’s Liberation Army. “The dip seems to be isolated to air activity.”

“我们并没有看到通报的台湾周边解放军海军舰艇数量出现类似的下降，”华盛顿专家、战略与国际研究中心中国实力项目副主任布莱恩·哈特表示，“这种下降似乎仅局限于空中活动。”

“Given the timing and the number of potential factors at play, it’s hard to say what exactly is shaping this behavior right now,” said Mr. Hart, who is the deputy director of the China Power Project at the Center for Strategic and International Studies.

哈特说：“考虑到目前的时机和多种潜在因素的交织，很难确切说明究竟是什么在塑造当下的这种行为。”

He and other experts, as well as Taiwanese officials, will be watching to see whether the flights increase after China’s legislative session.

他和其他专家以及台湾官员将密切观察在中国立法会议结束后，飞行次数是否会回升。

今年1月，台湾士兵在台中举行的一场军事演习中展示青天白日旗。

Some analysts also said that Mr. Xi may be dialing back the flights ahead of the meeting with Mr. Trump in Beijing, which is scheduled for early April, to bolster his argument that it is Taiwan, and not China, that is provoking tensions between the sides.

一些分析人士还表示，习近平可能会在4月初北京会见特朗普之前减少飞行，以支持他的论点——在台海煽风点火的不是中国而是台湾。

Beijing has cast President Lai Ching-te of Taiwan as a dangerous separatist bent on rejecting the prospect of unification, and risking war. Many Taiwanese and many Western governments see China as being the aggressor, including through military exercises that simulate an invasion or blockage of the island.

北京将台湾总统赖清德定性为危险的“分裂分子”，认为他执意拒绝统一前景并甘冒战争风险。而许多台湾民众和西方政府则认为是中国咄咄逼人，包括通过模拟入侵或封锁岛屿的军事演习来施压。

Given that Mr. Trump’s administration is already engaged in war with Iran, “I think that Xi doesn’t want Trump to think that Beijing is adding to the trouble,” said Ou Hsi-fu, a deputy chief executive officer at the Institute for National Defense and Security Research, a body in Taipei that receives funds from Taiwan’s government.

考虑到特朗普政府已经卷入了与伊朗的战争，“我认为习不想让川普觉得北京在添乱，”受台湾政府资助的台北国防安全研究院副执行长欧锡富表示。

“Beijing wants the Xi-Trump summit to go ahead smoothly, maintaining China’s image as a great power on equal footing with the United States,” Mr. Ou said.

“北京还希望川习会顺利进行，保持与美国平起平坐的大国形象，”他说。

The military flights are the mostly widely noted public measure of Chinese military pressure on Taiwan; they have increased since 2020, accelerating after Nancy Pelosi, then the speaker of the U.S. House of Representatives, visited Taipei in 2022. China retaliated against that visit by flying jets, sailing ships and even firing missiles around the island.

军机飞行是外界关注度最高的中国对台军事压力指标；自2020年以来，此类活动不断增加，并在2022年时任美国众议院议长南希·佩洛西访问台北后加速。当时，中国通过出动战机、舰艇甚至在岛屿周边发射导弹进行了报复。

Some experts believe that the current reduction in flights may reflect disruption caused by the official purges in the Chinese air force, including in the Eastern Theater Command, the region of the Chinese military that oversees Taiwan. The Chinese armed forces have been shaken by widespread purges of generals and other top leaders.

一些专家认为，目前的飞行减少可能反映了中国空军内部官员清洗所导致的干扰，包括负责监督台湾区域的东部战区。中国武装力量此前因将领及其他高层领导人的广泛清洗而产生动荡。

Another possible factor may simply be that the air force is intentionally altering its training routines, said K. Tristan Tang, a nonresident fellow at the National Bureau of Asian Research.

美国亚洲研究局非常驻研究员汤广正(K. Tristan Tang)表示，另一个可能的因素或许只是空军在有意改变其训练常规。

“What we are seeing now has actually been developing for more than half a year,” Mr. Tang said, citing a recent pattern of more days without flights compared to the previous year. “The difference is that the decline has become much more noticeable recently.”

“我们现在看到的现象实际上已经发展了半年多，”他是指近期与去年相比，出现了更多“无飞行日”模式。“不同之处在于，这种下降在最近变得更加显而易见。”