Chinese state television ran footage of troops storming a mock-up of Taiwan's presidential palace

Earlier this month, Chinese state TV ran video of People's Liberation Army soldiers storming a mock-up of Taiwan's presidential palace during a major military exercise in northern China, according to the Wall Street Journal.

This is just about as provocative as state-sanctioned propaganda gets.

The video is a depiction of Chinese forces overthrowing a US-allied elected government, an improbable - yet not entirely impossible - event that would throw the global-security environment into chaos if it ever happened in reality.

Rival governments have ruled Taiwan and mainland China since 1949. In the ensuing decades, the mainland People's Republic of China has emerged as an authoritarian economic powerhouse. Meanwhile, the Republic of China in Taiwan developed into a US ally and a democracy, with one of the 20-largest economies on earth.

Only 22 foreign governments recognize Taiwan as an independent country (the US withdrew recognition in 1979). But mainland China's failure to actually govern the island has created a stable status quo. In return for the international community's recognition of Beijing's right to the island, Taiwan has received a kind of de-facto independence, enjoying many of the benefits of statehood without the international tension - or perhaps even regional war - that would result from China actually trying to assert territorial control.

Future Chinese leaders may decide this status quo is no longer in the best interests of the People's Republic. One option is a full-on invasion of Taiwan.

Such a scenario would be just a shade less worrying than tactical nuclear war as far as geopolitical nightmare scenarios go - a Chinese invasion has the potential to topple an elected pro-American government, unsettle already-jittery neighboring states, and reshuffle the balance of power in East Asia in ways that probably wouldn't work to the US or its allies' advantage. An invasion would likely cancel out the US "pivot to Asia," the Obama administration's policy of shifting US military and diplomatic focus to East Asia in order to counter-balance China's rising hard power in the region.

A Taiwanese D-Day wouldn't be cost-free for China: There would be international condemnation and the potential loss of thousands of troops with little obvious clear-cut gain, along with the very real possibility of external or even US military involvement. But Beijing has strong incentive to keep up a credible threat of force. The possibility of invasion warps the island's politics in Beijing's favor, while reminding other international actors of China's immense leverage over the island's future.

The result of this dissonant policy is saber-rattling like the state-run video. As The Wall Street Journal reports, the simulated attack on a specific national landmark might be meant to influence Taiwan's politics, and could be be "an attempt by Beijing to send a signal to Taiwan's main opposition force, the Democratic Progressive Party." The DPP is a pro-Independence party and the current leader in the polls for a January 2016 national election.

As the Journal reports, Beijing may also want to remind Taiwan and its leadership that it still has active invasion plans, even if it has proven unwilling to actually go through with them.

"Over the years, the PLA threat to Taiwan has become largely abstract, and ordinary Taiwanese now tend to shrug off news of traditional PLA exercises," J. Michael Cole, a Taipei-based scholar with the University of Nottingham, told The Wall Street Journal.

The footage is aimed at shattering that complacency. Beijing wants to restore credibility to its threat of force for Taiwanese themselves.

Even so, this could be too optimistic a read on the video, which gives little idea of whether China's willingness to violently resolve the Taiwan issue has actually changed under Chinese premiere Xi Jinping, who is considered to be one of the most nationalist and authoritarian leaders in China's post-Mao history.

And it's the unknown of Beijing's threshold for resorting to a full invasion is part of what's made the island's sovereignty one of the world's prickliest and most dangerous political fault lines of the past 60 years.

Here's the full video: