When justice is done, it brings joy to the righteous but terror to evildoers. ~ Proverbs 21:15

Make no mistake, justice has been done. A mass murderer, a war criminal, and the leader of an international terrorist enterprise fell. He fell not in an air strike or drone attack, but in an operation that is far more emblematic of our long war: A direct, high-risk, up-close-and-personal raid by courageous and meticulously trained American soldiers.

When the news came, I was caught off guard by my emotions. I was joyful, but I thought immediately of the men with whom I served in Iraq who were not alive to see this day. These were men who chose to disrupt their lives following September 11, 2001, who chose to volunteer, to deploy, and to fight a horrific evil. They would have savored this moment, just as we savored many moments "downrange" when we killed or captured the al Qaeda leaders and thugs who so terrorized our own little corner of the world.

Osama bin Laden brought an ocean of suffering into this world, and his death—while temporarily easing that pain and bringing grim satisfaction—will not end the suffering. Unlike many pundits, I'm not concerned about his "martyr" status. Jihadists thrive on victory, not defeat, and this defeat will demoralize them even as they will, no doubt, seek vengeance. The martyrdom a jihadist covets is not a bullet in the head in a midnight raid but instead a blaze of glory where infidels die and their mission is accomplished. This will be a shock to al Qaeda and a source of mourning.

But it won't stop the war. Although al Qaeda was undeniably responsible for 9/11, it's a mistake to equate our war against Islamic terrorism with a war against al Qaeda. We are fighting an international jihad, of which al Qaeda is but one head of a hydra. Killing Osama bin Laden does not stamp out the theology he embodied. And in fact, even through the joy of a successful operation, there are troubling signs.

Why was bin Laden able to live in a mansion in the heart of Pakistan? How did he escape detection? Did the Pakistani ISI—which is known to have pro-Taliban sympathies and on occasion provide them aid—also give aid and comfort to Osama bin Laden? If so, then we may have much greater challenges in Pakistan than we'd previously imagined.

We know that the jihadist theology not only animates al Qaeda and the Taliban. It also dominates Iran, portions of Pakistan's government (and indeed entire Pakistani tribal regions), it dominates Gaza and now perhaps all of the Palestinian Authority with the announcement of the "reconciliation" or "unity" agreement between Hamas and Fatah. And the murderous Syrian government has long provided material support to Jihad. The names of jihadist groups roll easily off the tongue. There's not just al Qaeda, the Taliban, and Hamas, but there's Hezbollah, the Iranian Revolutionary Guards, the al Aqsa Martyr's Brigade, JAM (Muqtada al-Sadr's militia in Iraq), and, perhaps most ominously, the Muslim Brotherhood, which is gathering strength in Egypt.

Killing Osama bin Laden will no more end the war than killing Abu Musab al-Zarqawi ended the insurgency in Iraq. Indeed, after Zarqawi died some of our darkest days still lay ahead.

As we learned in Iraq, defeating Jihad does require killing and capturing its charismatic leaders, but it also requires stamping out terrorist cells one by one and taking cities neighborhood by neighborhood, all while doing everything in our power to discredit its animating ideology and elevating alternative leadership in the Muslim world. It is the fight of our lifetimes, and—if history is any indication—a fight that will continue long after we are gone.

These sobering truths should temper our joy, but joy should remain. There is enormous value in justice, and the message of our relentless pursuit will resonate far and wide. When Osama bin Laden struck America on 9/11, he imagined that he was striking a morally weak country, a country with no stomach for a long and tough fight.

Almost ten years later, he discovered how wrong he was.