TAIPEI - The widely expected visit to Taiwan by US House Speaker Nancy Pelosi is being watched keenly by political observers and ordinary Taiwanese alike.

Premier Su Tseng-chang on Tuesday (Aug 2) said Taiwan "warmly welcomes" foreign guests, and that the island "would make the most appropriate arrangements" for such guests and respect their plans.

Mr Eric Chu, chairman of main opposition party Kuomintang, also said he welcomes "visits from international friends, as long as the visits are beneficial to Taiwan's regional security, economy, trade, democracy and freedom".

Mrs Pelosi is on an Asia tour that started in Singapore on Monday, followed by Malaysia on Tuesday, before heading to South Korea and Japan. There was no mention of Taiwan when her itinerary was announced on July 31.

A US airforce jet that flew Mrs Pelosi to Malaysia left the capital Kuala Lumpur on Tuesday afternoon, according to flight-tracking website Flightradar24 and Reuters witnesses.

Reuters could not immediately establish if Mrs Pelosi or her delegation were on the plane.

Media reports said Mrs Pelosi was expected to arrive in Taipei on Tuesday night, and that she would visit the Legislative Yuan, or the Parliament, and meet President Tsai Ing-wen on Wednesday.

While visits from US politicians in the past had been viewed positively by ordinary Taiwanese, some people, however, are feeling anxious this time round.

"People have been saying that China may fly warplanes and, perhaps, even fire missiles as (Mrs Pelosi) plans to land... this is giving me a lot of anxiety," said Dr Mike Chang, 33, a surgeon based in Taipei.

On Tuesday, Reuters reported that several Chinese warplanes flew close to the median line dividing the Taiwan Strait. It was also reported that a number of Chinese warships had remained close to the unofficial dividing line since Monday.

A video by the Eastern Theatre Command of the People's Liberation Army, which showed scenes of military exercises and preparations and was posted on state media sites on Monday evening, urged troops to "stand by in battle formation, be ready to fight upon command, bury all incoming enemies".

In response, Taiwan's troops reportedly began preparations on Tuesday, adjusting their combat readiness in case China does launch an attack.

Its Defence Ministry said that the military was prepared to send "appropriate armed forces according to the threat".

It added: "The military is determined, confident and capable of ensuring national security."

Analysts, meanwhile, are less concerned about an immediate conflict and see the visit as more of a personal achievement for Mrs Pelosi.

"I think the visit itself is a good thing; there is no negative implication," said Professor Chen Fang-yu from the Department of Political Science at Soochow University in Taipei. "This is likely (Mrs Pelosi's) last time travelling as House Speaker. This is like a wrap-up consistent with her image as a leading figure in the democratic world."

Former Democratic Progressive Party legislator Julian Kuo agreed.

"She is 82... there is no reason she should be worried about the upcoming mid-term elections, so (I think) the stopover in Taiwan is happening, and it would be a personal achievement for her," he said.

Still, experts are worried about how the potential visit would aggravate further the tension between China and the United States.

Prof Chen said that even if Mrs Pelosi ended up not making a stop in Taiwan, the threat that China poses to the island will continue to exist.

Mr Eric Gomez, the director of defence policy studies at American think-tank Cato Institute, thinks that Mrs Pelosi's visit is a "high-profile vignette of larger and more worrying developments in cross-strait relations".

Rather than sparking immediate military action that some Taiwanese are worried about, the trip by itself is unlikely to start a new crisis across the Taiwan Strait, he said.

"But it is indicative of a bigger spiral of tension that could lead to a serious crisis, or even an armed conflict, between the United States and China."

Both sides believe that the other is attempting to undermine decades of political consensus that keep the peace in the Taiwan Strait, he added.

China has warned repeatedly against Mrs Pelosi's unannounced visit to the island, saying that Beijing will take strong actions to thwart any external interference or "Taiwan independence" separatist scheme. It has also said that it will be resolute in safeguarding its national sovereignty and territorial integrity.

Beijing sees Taiwan as a renegade province to be reunified, by force if necessary.

China on Tuesday (Aug 2) said it was in communication with the US over Mrs Pelosi's expected visit to Taiwan, warning that Washington will "pay the price" if the trip goes ahead.

"What I can tell you is, the US will definitely have to bear responsibility and pay the price for harming China's sovereignty and security interests," foreign ministry spokesman Hua Chunying told a regular press briefing in Beijing, adding that China will take "firm and powerful" measures in response.

"If the US misjudges or handles the situation across the Taiwan Strait incorrectly, it will have catastrophic consequences for the security, prosperity and order of the Taiwan region and the world at large."

In a regular briefing on Tuesday afternoon, Taiwan's Foreign Ministry said it could not comment on the speculation around Mrs Pelosi's trip.

"Taiwan always welcomes international visitors coming to Taiwan to gain a better understanding of Taiwan and to display their support for Taiwan," ministry spokesman Joanne Ou told reporters.