While candidate Trump spouts anti-Muslim rants, elected officials on both sides of the Atlantic are pressing ahead with plans for military action that will shed real blood. The British Parliament just voted to join French airstrikes in Syria. US lawmakers, prominent democratic senators included, are pressing for a formal declaration of war against ISIL.

European powers have learned the virtues of peace at home. But, as the UK vote shows, the curse of waging war in faraway lands continues.

Lest we forget: European colonial powers subjugated vast territories and populations in Africa and Asia through duplicity and force; they departed amidst extensive violence. The French scorched earth conquest of Algeria in 1830 featured massacres and mass rapes. A century later, the Algerian war of independence left about a million dead. Scores of wars and the suppression of a rebellion in which British troops executed rebels trussed to the muzzles of cannons secured British rule in India. A chaotic partition that came with Indian independence in 1947 left at least half a million dead and twelve million homeless.

Subjugation sustained a backwardness whose consequences were just as grim. The industrial revolution dramatically increased incomes, lifespans, and literacy in Europe. Abroad, colonial governments neglected to provide the schools, roads, sewers, and other prerequisites for industrialization; powerless, unenfranchised natives endured widespread illiteracy and squalor, unconscionable infant mortality, hunger, and periodically, devastating famine. In 1943, for instance, about three million people starved to death in Bengal.

Colonies abroad did not help many back home either. Britain was the cradle of the industrial revolution, but frittered away blood and treasure on an unwieldy empire. Germany and other European countries who channeled their entrepreneurial energies on building industrial powerhouses such as Siemens and Bayer leapt and stayed ahead to the great benefit of ordinary citizens.

Many of the would-be shooters and bombers in London and Paris are the progeny of immigrants from benighted colonies who came to do menial work.

As with many military adventures today, the rhetoric of morality and principle cloaked the deadly imperial enterprise. The savagery and cannibalism of African tribes (worse than ISIL even) justified their slaughter. India was gradually gobbled on the pretext of deposing despots who, like Saddam Hussain, invaded neighbors. British and French troops marched into Beijing and sacked the Summer Palace in 1860 to enforce the principle of free trade, including notably the right to sell opium to the Chinese.

Harsh colonial rule and an aura of invincibility secured broad but not total compliance. I have on my shelves books my father bought in the early 1940s, variously titled Chemicals in War, and The Chemistry of Powder and Explosives. My father, then enrolled for a PhD in physics, somehow figured out how to make bombs launched against British targets in Bombay from books published in New York by McGraw-Hill and Wiley and Sons. And although he was certainly not a non-violent Gandhian, he wasn’t a fanatical firebrand either. After independence, he built a sizable business—and retained no grudges against the British.

Britain and France now face a deadly blowback from their forgotten pasts. As empires dissolved, so did the ingrained subservience of Rudyard Kipling’s “silent sullen peoples.” Colonial governments had ruthlessly suppressed dissent, persuading multitudes that resistance was futile. Now firebrand clerics are unchallenged in preaching that victory against Western infidels is certain.

While the new bombers may be ragtag misfits, their arsenals aren’t kludged together by self-taught bomb makers. A global bazaar sells sophisticated, easy-to-use explosives and guns to any paying customer.

Restraint in faraway lands has been abandoned in the past several decades, particularly in the Islamic world, with little understanding of the long-term consequences.

Worse, the malevolence has come home. Many of the would-be shooters and bombers in London and Paris are the progeny of immigrants from benighted colonies who came to do menial work. Their offspring, who aren’t much better educated than their parents but won’t do the jobs local Caucasians spurn, are natural recruits for martyrdom. Not all certainly, but it doesn’t take battalions to kill and maim many in a dense metropolis.

Raining more bombs in the Middle East that will unavoidably shed innocent blood to stop terror at home is folly. Even if ISIL could be defeated from the sky, another Western-led regime change is highly unlikely to quell brutality in the Middle East or blunt the fervor of zealots in European capitals. And expelling or interning anyone who might turn to violence is just not an option.

Washington isn’t helping. American revolutionaries fought a war to secure independence from British rule and as the US became a world power it did not seek an empire. But restraint in faraway lands has been abandoned in the past several decades, particularly in the Islamic world, with little understanding of the long-term consequences. Willy nilly, dictators have been installed or deposed, and democratic movements have been favored and suppressed. American weapons and training provided to armies and shadowy groups—Saddam’s forces battling Iran, the mujahedeen fighting the Soviets in Afghanistan (with Osama Bin Laden in a starring role), and most recently Syrian rebels attacking Assad—have been turned against US soldiers. Yet politicians and experts who blundered monumentally in the past cry on for more, again in the name of keeping Americans safe.

The British experience with Irish Republican Army bombers suggests that there is no quick military fix. The IRA too arose out of brutal centuries-long colonial oppression and poverty, was financed by sympathizers in Boston and New York, and equipped with arms provided by Libya. It too could recruit from disaffected Irish living in London. That threat was defused without retaliatory air-strikes (or demonizing Catholics) by resolute police and intelligence work. But it took decades of forbearance, and a settlement that included the IRA’s political wing, its previous brutalities notwithstanding.

“The West won the world not by the superiority of its ideas or values or religion” Samuel Huntington wrote in The Clash of Civilizations, “but rather by its superiority in applying organized violence. Westerners often forget this fact; non-Westerners never do.”

But organized violence abroad has yielded a bitter harvest in the West. Its time to stick to the ideas and values that can provide better lives for all.