In the 12 years since 9/11, the United States has been consumed by fear of Islamist terrorism.   Underpants bombers, Guantanamo prison, torture, Bin Laden, drone attacks — the list of news stories and issues related to conflicts between radical anti-Western jihadis and the West, and American efforts to prevent their attacks, goes on and on.

Until this week, U.S. law enforcement efforts succeeding in stopping any attacks on U.S. soil.  This week, the terrorists succeeded.

But who are these terrorists?   Kids, top students, long-time U.S. residents, one an American citizen.  Radicalized how?  By the violence in Chechnya, their homeland?  Or by the internet?  Or by experiences here?

Sadly, the basic grievances that fueled Jihad — illegitimate governance, crony domination, lack of justice, lack of opportunities — are still rampant in the world, despite the Arab Spring.  A few countries may have shed their dictators, but that does not mean that justice and opportunities have arisen.  And in many countries — Afghanistan, Syria, Yemen, Iraq, Sudan, and the province of Chechnya, to name just a few — huge cohorts of young men encounter illegitimate government, corruption, and violence on a daily basis.  This much is old, that is true.  What is new is internet-fueled recruitment and hate speech, instructions on how to commit terrorism, and easy travel between hot-beds of unrest and Western nations.

Perhaps even worse, the promise of opportunity and acceptance in the liberal nations of the West is often a promise denied.  Islamophobia, anti-migrant sentiment, high unemployment, diminishing opportunity for the working and middle classes, blatant conspicuous consumption and self-righteousness by the ever-richer rich all make it easier for frustrated youth to justify striking out at any target.

Terrorists are criminals, and we need to punish the crimes and do all we can to deter criminal action.  Yet let us not fool ourselves.  We live in a world of ever-rising inequality, pervasive youth frustration, and deep distrust across regions and religions.  We will need to be on guard for a very long time.