Donald Trump, front-runner to be the GOP's candidate for the upcoming US presidential election, encountered a major protest at his campaign event in Chicago on Friday evening. Over a thousand people, both his supporters and opponents engaged in a physical confrontation, which was quelled by police who arrested a number of people.

Fist fights among voters who have different political orientations is quite common in developing countries during election seasons. Now, a similar show is shockingly staged in the US, which boasts one of the most developed and mature democratic election systems.

Trump's mischief has overthrown a lot of conventional norms of US political life.

His remarks are abusively racist and extremist, which has left an impression on the US public that he is intentionally overthrowing political correctness.

Trump's rise was not anticipated by most analysts and observers. At the beginning of the election, Trump, a rich, narcissist and inflammatory candidate, was only treated as an underdog. His job was basically to act as a clown to attract more voters' attention to the GOP. However, knocking down most other promising candidates, the clown is now the biggest dark horse.

Trump is the last option for the GOP establishment. If he wins the primaries, the GOP will face a bitter dilemma. On the one hand, it will be a big compromise to GOP values, and the party takes a major risk of losing the game if they choose Trump as their candidate for president; on the other hand, if the GOP refuses to choose Trump, he might run as an independent candidate and split the vote, in which case, the GOP will also stand no chance in the final game.

The rise of Trump has opened a Pandora's box in US society. Trump's supporters are mostly lower-class whites, and they lost a lot after the 2008 financial crisis. The US used to have the largest and most stable middle class in the Western world, but many are going down.

That's when Trump emerged. Big-mouthed, anti-traditional, abusively forthright, he is a perfect populist that could easily provoke the public. Despite candidates' promises, Americans know elections cannot really change their lives. Then, why not support Trump and vent their spleen?

The rise of a racist in the US political arena worries the whole world. Usually, the tempo of the evolution of US politics can be predicted, while Trump's ascent indicates all possibilities and unpredictability. He has even been called another Benito Mussolini or Adolf Hitler by some Western media.

Mussolini and Hitler came to power through elections, a heavy lesson for Western democracy. Now, most analysts believe the US election system will stop Trump from being president eventually. The process will be scary but not dangerous.

Even if Trump is simply a false alarm, the impact has already left a dent. The US faces the prospect of an institutional failure, which might be triggered by a growing mass of real-life problems.

The US had better watch itself for not being a source of destructive forces against world peace, more than pointing fingers at other countries for their so-called nationalism and tyranny.