The US, availing itself of 9/11, worked out a new concept of war, "war on terror," and declared a war against terrorism throughout the world.
It drew the curtain of the war by launching military operations against Afghanistan with the purpose of eliminating Osama bin Laden and al-Qaeda.
Since then, the US has fought hard to "stamp out" terrorism and "defend" democracy in Iraq, Libya, Syria and so on; but instead of achieving the set purpose, it threw the world into a greater confusion.
Still now, the US is drawn into quagmire in Afghanistan and Iraq, and al-Qaeda, once considered to have been stamped out, has raised its head, emerging as a more dangerous terrorist group.
The sectarian religious contradiction and social chaos prevalent in Iraq have thrown the US into perplexity. ISIS, an international terrorist organization, which emerged and grew in strength amidst the US "war on terror," is committing acts of terrorism across the world, going beyond the bounds ones of the relevant countries and region.
Counterterrorism, which the US once clamoured for loudly, has now produced political instability, social disorder, ethnic disputes and refugee crisis in many countries of the world.
It can be said that the US opened the Pandora's box with the key, called counterterrorism.