The atrocities committed in the latest Paris attacks rightly horrify us, but they should surprise no one, least of all the French. An outraged President Francois Hollande announced that “France is at war,” but of course that had been the case for more than a year, since France started bombing Islamic State forces in Iraq and later in Syria. Why did he only announce the fact after French citizens had died? He apparently hoped that the war would not inconvenience his own people, perhaps that they wouldn’t even notice the conflict.

Terrorism is monstrous. The targeting of civilians is morally wrong. However, it is sadly predictable, an almost common practice by weaker powers. A century ago an ethnic Serb triggered World War I with a terrorist attack. In recent years the most prolific suicide bombers were Tamils, fighting against the Sinhalese-dominated government of Sri Lanka. Sunni opponents of the newly empowered Shia majority in Iraq eventually took the lead in employing this hideous tactic. Now the Islamic State appears to be perfecting a weapon it had heretofore left to al-Qaeda.

There’s no mystery as to why. It wasn’t an attempt “to destroy our values, the values shared by the U.S. and France,” as claimed by Frederic Lefebvre of the National Assembly. Rather, admitted French academic Dominique Moisi, the Islamic State’s message was clear: “You attack us, so we will kill you.” By now every government should recognize what America learned on September 11, 2001. Wandering the globe bombing, invading, and occupying other states, intervening in other nations’ political struggles, supporting repressive governments, and killing residents for good or ill inevitably create enemies and blowback. Explanation is not justification. But any government that attacks the Islamic State should realize retaliation is likely, probably against people innocently going about their lives, as in Paris–and against Hezbollah in Beirut the day before and Russia in Sharm el Sheikh a bit earlier still.

… Kumar Ramakrishna of Singapore’s Nanyang Technological University argued that the Islamic State made a simple strategic calculation: it cannot defeat the allies’ conventional forces, but can hope to “raise the domestic costs of Western coalition diplomatic and military involvement in Syria and Iraq.”