Speaker of the House Nancy Pelosi arrived in Taiwan on Tuesday for a trip that had sparked earlier warnings from Beijing that China's military “won’t sit idly by” if the visit occurs. A day earlier, the White House urged China not to overreact to Pelosi’s likely visit. And while Joe Biden went to great lengths to clarify to Chinese president Xi Jinping that Congress acts independently from the White House, the United States Administration had expressed reservations about Pelosi’s plans.

But how will people in Taiwan perceive this type of high-level visit? After the Russian invasion of Ukraine in late February, Taiwanese citizens have become less confident about the likelihood of US intervention in the case of a military crisis. Our ongoing research finds that high-level visits can be an important way to reassure weaker partners about the strength of the alliance.

Taiwanese have become less certain about U.S. support

Taiwan has faced the threat of forceful unification with China for many decades. The island has relied on an implicit US security commitment and arms sales to support its defence. The United States has long followed a policy of “strategic ambiguity” and does not specify what actions it would undertake if a Chinese attack on Taiwan occurred. This policy of strategic ambiguity allows the United States to maintain flexibility — in itself a form of deterrence. But pro-China groups in Taiwan point to the policy as evidence that the United States is an unreliable partner.

However, Russia’s war in Ukraine appears to be changing Taiwan’s perception of the US security commitment. A March survey in Taiwan, for instance, found that roughly one third of respondents believed the United States would offer military aid to Taiwan. That is a steep decline from the two thirds who believed the US would support Taiwan militarily when the same institute asked this survey question last October.

The importance of high-level visits

In international relations, strong countries often need to reassure their weaker partners. If partners are uncertain a stronger power will come to their aid, this could motivate a weaker partner to abandon the alliance altogether. And research suggests that weak partners could even shift their allegiance and line up with the country they find threatening if they perceive the threat to be insurmountable and don’t get reassurances to the contrary from their stronger partner.

Do high-level visits provide this type of reassurance? Our recent survey explored the effects of a high-level US visit on public support for national security policies in Taiwan. We utilised a trip by three high-profile US senators in June 2021 as a quasi-experiment, as their visit occurred during the survey. The delegation that visited Taiwan included Tammy Duckworth, the Democrat from Illinois, Dan Sullivan, the Republican from Alaska, and Chris Coons, the Democrat from Delaware.

We conducted an online survey with 1,500 Taiwanese participants, designed by Taiwan’s Institute for National Defence and Security Research and implemented by the Election Study Centre at National Chengchi University, Taipei. The survey polled 1,100 respondents before the US senators' visit and 400 afterward. Our survey found that the June 2021 visit significantly increased respondents’ confidence in Taiwan’s military. Moreover, we found that the effects hold across different political groups, which suggests the impact of the visit by the US senators was not the result of partisanship or nationalism within the survey sample.

Our continuing research also indicates that a visit from a stronger country’s leader is likely to push the smaller partner’s public to be more supportive of the great power’s preferred security policy — and, in this case, boosting support for the Taiwan’s defence budget or strengthening Taiwan’s self-defence capacity to share the US security burden. And the Taiwanese public may also be more supportive of the incumbent government and its ability to implement the US preferred security policy.

Taiwan is increasingly concerned about China

Are there takeaways from other polls? An October 2021 opinion poll, for instance, asked whether Taiwanese citizens strongly agree, somewhat agree, somewhat disagree or strongly disagree with the statement that China will eventually attack Taiwan.

Most of the respondents were optimistic that China will refrain from aggression — only 28 per cent said they think China will attack Taiwan, while more than 64 per cent felt that military aggression is unlikely. This confidence probably stems from experience. The Taiwanese people have been exposed to such threats from China for 70 years, but the island itself has never come under direct attack.

But those October poll results also suggest an increased concern over aggression from China. In the 2019 version of this poll, about 80 per cent of respondents disagreed with the statement that China will eventually attack Taiwan. And the percentage of people who chose “strongly disagree” on the question of whether China would attack dropped from 42 per cent in 2019 to about 24 per cent in 2021.

What explains the rising levels of concern? It is no secret that Chinese leader Xi Jinping has upped the tough rhetoric on Taiwan. In a January 2019 speech, he remarked, “we make no promise to renounce the use of force and reserve the option of taking all necessary means." This statement struck many Taiwanese and foreign observers as a blunt but clear indication of Xi’s intentions. And China’s clampdown on Hong Kong after the widespread protests against the proposed 2019 Anti-Extradition Law also shocked many in Taiwan.

The importance of high-level visits to Taiwan

Pelosi’s stop in Taiwan could be a dangerous moment in US-China relations. But our research suggests that the visit would probably significantly reassure the people of Taiwan, enhancing public support on the island for military and defence spending as well as US strategic policy goals.

• Yeh Yao-Yuan is Fayez Sarofim-Cullen Trust for Higher Education endowed chair in international studies, chair of the International Studies & Modern Languages Department and chair of the Political Science Department at the University of St Thomas in Houston

• Chen Fang-Yu is assistant professor of political science at Soochow University, Taiwan

• Austin Horng-En Wang is assistant professor of political science at the University of Nevada, Las Vegas

• Charles K.S. Wu is assistant professor of political science at the University of South Alabama