A 17-year-old Afghan young man attacked four tourists from Hong Kong on a train in Bavaria, southern Germany, with an axe and knife on Monday night. Police shot him dead as he attempted to flee the scene. The perpetrator reportedly shouted "Allahu akbar" (God is greatest) as he stabbed people. According to local officials, a hand-painted flag of the Islamic State was found in the assailant's room.

The teenager entered Germany as an unaccompanied child refugee and previously lived in a refugee camp. It's still unknown whether he is a member of radical groups or just motivated by extremism.

The IS on Tuesday claimed responsibility for the attack, saying the perpetrator is their "fighter."

The train assault is not as severe as the other recent atrocities in France, but it's a shock to Germany and Europe that cannot be overlooked. Germany in recent years has been rarely hit by grave terrorist attacks despite being the biggest recipient of asylum seekers from the Middle East. But given this assault, Germans cannot be obsessed with the illusion that they have had lucky escapes from the wave of terrorist attacks any more.

Almost all terrorist attacks in Europe in recent years are waged by Islamic extremists, be they migrants or born in the country. However, asserting that the time for a clash of civilizations, proposed by political scientist Samuel P. Huntington, has come is still far-fetched. National interests continue to dominate varied power games.

Among the European immigrants, Muslims constitute the majority of the disadvantaged group. Worldwide, Islamic countries hold a weak position. States usually stick to the bottom line of rationality. But it's a different thing when it comes to certain forces or individuals.

This is not clash of civilizations, since the two parties are not on an equal footing. A slim number of frustrated people, most of whom are lone wolves, are becoming radicalized. They only have spiritual links with a distant terrorist center, but they are devastating enough to strike unbearable blows to modern society.

Apparently, Europe has entered into a vicious circle. Anger and distrust have increasingly expanded between local residents and new immigrants. Europe is in for a nervous time, as a good solution is still out of reach.

Europe is not alone, as the US may not be able to separate itself from the menace. Even though it has largely been successful in warding off terror attacks, it remains a top target for terrorists. If Europe falls to terrorism, the US will suffer also.

Terror attacks today are very different from the era when Al Qaeda took the lead. Anti-terrorism will be a more pressing task than geopolitical competition for the West.

Terrorism will bring subversive effects if it is not effectively checked. Change, which might be unthinkable today, could happen to the West. Brexit and the emergence of Trump may only be the start of the change.