The vacuum that Barack Obama left in the Middle East brought us the Islamic State, while Donald Trump's cluelessness brings us Iranian Shiite militias. The lesson learned from 9/11 haunts America to this day: Leave the jungle and it will find its way to your front door. But has this lesson been internalized?

The mega-attack that led to the collapse of the World Trade Center in Manhattan and the death of thousands on Sept. 11, 2001 brought the world into turmoil. Two key lessons emerged from the event: a strategic lesson that freedom has limits, and a tactical lesson that one cannot flee the Middle East without dire consequences.

In early 2001, President Bill Clinton passed the baton to George W. Bush. Those were euphoric times in America; the country was captivated by the Bill and Monica scandal. Here in Israel, we were dealing with the fight against Yasser Arafat's intifada. At the time, Clinton tried to explain to us that only peace would bring us security, but even back then, we were already beginning to understand that this equation was wholly off the mark.

Slowly, it became clear to Israel that the sole condition for normalcy was to enter enemy territory in order to establish intelligence control. We realized that unless we reached deep into such territory, the enemy would come to us. This assumption, however, was rejected in the U.S., and every cross-border military operation by Israel was met with disapproval.

Then, one bright day, the skies above Manhattan collapsed on America. All at once, the U.S. understood that if you run away from the Middle East, it will simply follow you home. Only a few months later, America was already in another place. Its war was emotional. Little forethought was invested in the U.S. military response to 9/11, and so too, its achievements as a consequence. But the lesson America learned still haunts it to this day: Leave the jungle and it will find its way to your front door.

Though this lesson still echoes, liberals are unwilling to accept the fact that while freedom is important, it also has limitations. Perhaps the time has come to understand that we have gone too far, breaching the balance between private interest and public security. Nature, we learn, does not spare the intensity of pain due to man’s blundering.

Amazing as it may be, the Western world has yet to internalize these lessons. In every case where it extricates itself from “the swamp,” it receives in return a tsunami of mosquitoes with particularly painful stings. Even thousands of dead in Manhattan did not help to instill this lesson, and the world continues as if nothing has changed.

Thus, the vacuum that Obama left in the Middle East brought us the Islamic State group, while Trump's cluelessness brings us Iranian Shiite militias. But nature abhors a vacuum. The question is what will finally make the West understand this, and when will it begin to act accordingly — if at all.

The answer is difficult. Clearly, the West does not want to understand. Instead it will slowly sink into itself like the Titanic, whose captains did not believe it could go under, and all the while the orchestra continued to play.

At least we can say that here in our neck of the woods, we got the message long ago. Apart from a group of chronic depressives in retreat, it is clear to us all that if we are not “there,” the result will be that “they” will be “here,” and that if individual freedoms are not curbed, there won't be any greater good left to defend.

The author is a retired colonel in the Israel Defense Forces.