The announcement last week in Beijing that China wants to build a 200-km tunnel to connect Taiwan to the mainland has been met with deep skepticism in Taiwan, with one critic suggesting the plan might have been fueled by drink.

“These tunnel proposals were made after banquets and alcohol, and I have never heard of anyone who supports this,” said Hu Sheng-cheng, an economist widely tipped to become a leading figure in the government of president-elect Tsai Ing-wen of the Democratic Progressive Party, which comes into office in May.

Alcohol and banquets or no, the Taiwan-mainland tunnel has been kicking around for quite some time. China Railway Deputy Chief Engineer last week raised the temperature at the two-week meeting of the Chinese National People’s Congress, labeling the corridor technically and financially feasible despite Beijing’s increasingly strained economy and spiraling national debt. It would be longer than the combined lengths of the two longest existing undersea tunnels on earth, the Seikan tunnel in Japan and the Channel Tunnel between France and the UK.

Even if the tunnel is feasible, it is certain to be caught up in the strained political situation between Beijing and Taiwan, which has grown increasingly dismissive of China’s close embrace. In January elections, voters humiliated the Kuomintang, which favors a closer political relationship to the mainland, voting 56.1 percent for the Democratic Progressive Party to 31 percent going to the KMT and 12.8 percent to the splinter People First Party.

An American security expert with a close eye on the Taiwan Strait strongly advises the Taiwanese side against allowing this to ever materialize.

“If this is not a form of ‘invasion’ I do not know what is,” said Rick Fisher, Senior Fellow, International Assessment and Strategy Center. “Late in the last decade I spoke with an official from a government – that I shall not name – who was concerned that China was planning to start drilling such tunnels secretly as part of wider preparations for an invasion of Taiwan,” he said.

Fisher added that the concern then was that China was buying most of the world’s production of large tunnel drilling machines. While it is now known that most of this effort was directed at expanding China’s “Underground Great Wall” for concealing its nuclear missiles, one side effect benefit for China is that it has amassed such a huge inventory of large tunnel drilling machines that it realistically could just start to drill tunnels to Taiwan without any say so from Taipei, he added.

“There is simply no way around political realities – as long as the Chinese Communist Party is ruling China, it will regard and plan any such tunnel to Taiwan to have military and civilian uses. As long as the CCP is in power it makes no strategic sense for any democratic government in Taipei to agree to a cross-strait tunnel,” he added.

Political scientists commenting on China’s newest announcement by and large agree that it was an especially ill-advised move at this stage, given that cross-Taiwan Strait relations are set to sour after the inauguration of the new Taiwanese government in May. The DPP to which president-elect Tsai belongs staunchly opposes China’s unification agenda.

“This is a very odd suggestion for anyone other than someone looking at cross-Strait relations from Beijing’s perspective only,” said Steve Tsang, Director of the University of Nottingham’s China Policy Institute. “It is very unwise indeed, as no president of Taiwan could agree to it, and making Tsai reject this will just put the relationship between the Tsai Administration and the Xi Jinping Administration off to a bad start.”

Meanwhile, an editorial by China’s People’s Daily-affiliated Global Times gave in its two cents by reiterating that “China’s clear ultimate goal is unification, and the unification war is a long-term policy.”

“This political responsibility outweighs any sacrifice to build the Beijing-Taipei railway.” It then urged Taiwan, “as a province of China, to think more. Connecting Beijing and Taipei, is “natural and feasible, will create jobs, will make Taiwan overcome its geographic handicap and will bring Taiwan toward a more prosperous path.”

China in the past decade has gone on a huge railroad-building binge that now encompasses more than 19,000 km of high-speed rail track, to be extended to 20,000 km. by 2020 and costing hundreds of billions of dollars, raising concerns that revenues do not cover operating costs and may never do and potentially leaving China’s banks on the hook for a significant percentage of that, inspiring criticism that the project is as much about hubris as much as transport. The projected Taiwan undersea tunnel – roughly 200 km including approaches on either side of the 160 km strait at a depth of 30 meters -- would be the most expensive of the lot at RMB260-300 billion (US$40-46 billion). Trains traveling at 200km/hr would take one hour from Fujian Province’s Pingtan Island to Taipei.

Feasibility studies on the construction of a tunnel or bridge linking mainland China and Taiwan have been commissioned by Beijing for decades. The first Beijing-sponsored seminars on the feasibility of such a project were held in the late 1990s, with engineers, geologists and other experts from both China and Taiwan attending. Plans for bridges and dams were scrapped in the successive years, given the usually adverse weather conditions in the Taiwan Strait, so that experts settled on the idea of a tunnel crossing where the Straits is the narrowest, i.e., between Pingtan and northwest Taiwan’s county of Hsinchu.

According to China’s State Bureau of Oceanic Administration, the area in question features a comparatively stable geological structure and shallower water, is not situated in the region prone to strong earthquakes, and is thus suitable for tunnel construction.

In 2005, the official China-highway web site listed the construction of the 2,030 Beijing–Taipei Expressway, which would connect the cities of Beijing, Tianjin, Jinan, Tai’an, Hefei, Fuzhou and Taipei. Bridges have been built since to connect Fuzhou and Pingtan. There, the Chinese are establishing the “Pingtan Comprehensive Experimental Zone” – commonly nicknamed “Little Taiwan” by the Chinese media – which with the help of a great number of incentives has been luring Taiwanese small and medium scale enterprises, academia and even government officials to relocate from Taiwan. The Beijing–Taipei Expressway plan was abandoned in 2013.

Based on the newest plan, the Beijing-Taipei high-speed rail corridor would include four major sections, between Beijing and Bengbu, Anhui Province; between Bengbu and Hefei in Auhui; between Hefei and Fuzhou; and between Fuzhou and Taipei. The tracks between Beijing and Bengbu would be part of the Beijing-Shanghai High Speed Railway, which has been in operation since 2011. The lines connecting Bengbu and Hefei and Hefei and Fuzhou were launched in 2012 and 2015, respectively. But if the tracks are ever to reach Taipei, the political and economic situation is going to have to be altered materially.