Balloons Float Over Taiwan Before an Election. Experts See a Sign from China.

A surge in sightings of balloons from China flying over Taiwan has drawn the attention of the island’s military and struck some experts as a calculatedly ambiguous warning to voters weeks before its presidential election.

Taiwan’s Ministry of National Defense has reported occasional sightings of balloons floating from China since last month, and a surge in recent days, according to the ministry’s daily tally of Chinese military activities near the island. Official Taiwanese accounts about balloons were previously very sporadic.

The recent balloons have mostly stayed off Taiwan’s coast. On Monday, however, one flew across the island, according to the ministry’s descriptions of their paths. Of four spotted on Tuesday, three flew over Taiwan, and two passed through to the island’s east side, facing the Pacific Ocean. Another flew over the island on Wednesday.

The Taiwanese reports also noted some of the balloons’ proximity to the island’s military bases. Of the four reported on Tuesday, three were first detected 120 to 184 miles from the Ching Chuan Kang Air Base in the city of Taichung. Taiwan’s defense ministry declined to specify how close to the base they may have flown.

The balloons do not appear to pose an immediate military menace to Taiwan, a self-governed democracy of 23 million people that Beijing says is its territory. Taiwan’s defense ministry last month indicated that the balloons seemed to be for collecting data about the atmosphere, but it has declined to give details about the ones detected this week.

“The Ministry of National Defense is closely monitoring and tracking them, responding appropriately, and is also assessing and analyzing their drift patterns,” Maj. Gen. Sun Li-fang, a spokesman for the ministry, said on Thursday in response to questions about the balloons.

Taiwan has, so far at least, experienced none of the alarm that gripped many Americans last year when a hulking Chinese high-altitude surveillance balloon floated across the United States. China denied that the balloon was for spying, but Washington did not buy that line, and the dispute soured relations for many months.

Taiwanese people are used to Chinese military flights near the island, and news of the balloons has generally been met with calm, if not indifference.

The balloon flights may, nonetheless, be part of the “gray zone” tactics that China uses to warn Taiwan of its military strength and options, without tipping into baldfaced confrontation. The timing of the balloon flights, close to Taiwan’s election, was telling, said Ko Yong-Sen, a research fellow at the Institute for National Defense and Security Research, a think tank in Taipei funded by Taiwan’s defense ministry. Mr. Ko has analyzed the pattern of recent sightings.

“It’s more an intimidating effect in what happens to be a quite sensitive time, with we in Taiwan holding our election on Jan. 13,” Mr. Ko said in an interview. China, he said, “may want to tone it down. People say that it has recklessly used major weapons like planes and ships for harassment, so it’s shifted to balloons that can be used for a certain kind of lower-intensity intimidation and harassment.”

In the election, Taiwanese voters will choose a president and legislature, and Beijing has made no secret of wanting the governing Democratic Progressive Party to lose power. The party opposes Beijing’s claims to Taiwan, and have asserted Taiwan’s distinctive identity and claims to nationhood. Decades ago, the party endorsed independence for Taiwan but now says it accepts the more ambiguous status quo of democratic self-determination.

Lai Ching-te, the Democratic Progressive Party’s presidential candidate, has been leading in most polls up to Wednesday. But Hou Yu-ih, the candidate for the Nationalist Party, which favors closer ties with China, has trailed Mr. Lai by only a few percentage points in some recent surveys, and the Nationalists may emerge as the biggest party in the legislature, ending the Democratic Progressive Party’s majority.

When asked late last month about the initial reports of balloons near Taiwan, a spokesman for the Chinese Ministry of Defense, Wu Qian, did not confirm or deny any flights, but suggested that, as Taiwan was a part of China, any dispute over balloons crossing the median line between the two sides was moot. He also accused the Democratic Progressive Party of whipping up the issue “to swindle votes.”

In 1996, China’s attempt to use missile tests and menacing military drills to shape Taiwan’s presidential election failed, and this time, Beijing has not rolled out any major military exercises in the weeks before the vote. The balloons may augur a more fiery response from China’s leaders if they dislike the election result, said Ben Lewis, a military analyst based in Washington who maintains a daily data record of Chinese military activities around Taiwan.

“I think the number of overflights, and, even more, their timing, is still an escalation in the P.R.C.’s activities,” Mr. Lewis said by email, referring to the People’s Republic of China. “If nothing else, I’m taking this as a warning that the P.R.C.’s response to the election will likely be impossible to predict.”

The latest sightings were almost certainly not the first time that balloons from China floated over Taiwan, Mr. Lewis said. The Taiwanese defense ministry began regularly reporting Chinese military flights near the island in 2020, and their numbers have grown year by year and now include drones.

After a Chinese weather balloon was found last year on a small island controlled by Taiwan, Taiwan’s defense ministry said that most of the balloons swept in around the Taiwan Strait from December to February when, it noted, the “prevailing wind direction” helped them along.

Mr. Ko, the Taiwanese defense expert, said that he worried more about what theChinese military could do with more concerted use of high-altitude balloons over the island, like the one spotted over the United States last year, which could augment data collection using satellites and radar.

“The intelligence gathering from Taiwan would be even more serious,” he said. “This is something we’ve been concerned about, and it would be more troublesome.”