“We are at war. We are at war against al-Qaida, a far-reaching network of violence and hatred that attacked us on 9/11, that killed nearly 3,000 innocent people and that is plotting to strike us again.”

Thus did Barack Obama clear the air as to whether we are at war, and with whom and why.

Following his remarks, during a White House briefing by National Security Council aide John Brennan, Helen Thomas asked a follow-up question to which we almost never hear an answer: Why is al-Qaida at war with us? What is its motivation?

It was Osama bin Laden himself, in his declaration of war in 1998, published in London, who gave al-Qaida’s reasons for war:

First, the U.S. military presence on the sacred soil of Saudi Arabia. Second, U.S. sanctions causing terrible suffering among the Iraqi people. Third, U.S. support for Israel’s dispossession of the Palestinians. “All these crimes and sins committed by the Americans are a clear declaration of war on God, his Messenger and Muslims,” said Osama.

He began his fatwa quoting the Koran: “But when the forbidden months are past, then fight and slay the pagans wherever ye find them, seize them, beleaguer them, and lie in wait for them in every stratagem of war.”

To Osama, we started the war. Muslims, the ulema, must fight because America, with her “brutal crusade occupation of the (Arabian) Peninsula” and support for “the Jews’ petty state” and “occupation of Jerusalem and murder of Muslims there” was waging war upon the Islamic world.

Terrorism, the direct killing of civilians for political ends, is al-Qaida’s unconventional tactic, but its war aims are quite conventional.

Al-Qaida is fighting a religious war against apostates and pagans in their midst, a civil war against collaborators of the Crusaders and an anti-colonial war to drive us out of the Dar al-Islam. On Sept. 11, they were over here—because we are over there.

Nothing justifies the massacre of Sept. 11. But these are the political goals behind the 9/11 attack, and this is why Islamists fare well in elections in the Middle East. Tens of millions of Muslims, who may despise terrorism, identify with the causes for which Osama declared war—liberation of Muslim peoples from pro-American autocrats and Israeli occupiers.

Americans are being killed for the reasons Osama said we should be killed—not because of who we are, but because of where we are and what we do.

Consider. America lost 4,000 soldiers in six years in Iraq, with 30,000 wounded. Yet not one American of the 125,000 soldiers in Iraq was killed in December. Why not? Because we no longer conduct raids, patrol streets, kick down doors and pat down suspects. We have ended our combat operations, withdrawn to desert bases and seem anxious to go home. When we stopped fighting and killing them, they stopped fighting and killing us.

Most Americans today appear content to let Shia and Sunni, Arab and Kurd decide the future of Iraq. And if they cannot settle their quarrels without a civil-sectarian war, why should their war be our war?

According to Gen. Barry McCaffrey, we must now prepare for 300 to 500 dead and wounded every month in Afghanistan by summer.

Why are the Taliban killing our soldiers? Because we threw them out of power, took over their country and imposed the Hamid Karzai regime, and our troops, some 100,000 by fall, are the force preventing them from recapturing their country. We will bleed in Afghanistan as long as we are in Afghanistan.

But if, as Obama said, “we are at war with al-Qaida,” why are we fighting Taliban when al-Qaida is in Pakistan, Yemen, Somalia, and North Africa?

Hamas has used terrorism, but not against us. Hezbollah has used terrorism, but not against us since the bombing of the Marine barracks, a quarter-century ago. And our Marines were attacked in Lebanon because we were in Lebanon, intervening in their civil-sectarian war. Had the Marines not been sent into the midst of that war, they would not have been targeted.

When Ronald Reagan withdrew them, the attacks stopped.

Like Europe’s Thirty Years’ War—among Germans, French, Czechs, Dutch, Danes, Swedes, Scots and English, Catholics and Protestants, kings, princes and emperors—the Muslim world is roiled by conflicts between pro-Western autocrats and Islamic militants, Sunni and Shia, modernists and obscurantists, nationalities, tribes and clans. The outcome of these wars, the future of their lands—is that not their business, and not ours?

The Muslims stayed out of our Thirty Years’ War. Perhaps we would do well to get out of theirs. But as long as we take sides in their wars, those we fight and kill over there will come to kill us over here.

This is payback for our intervention. This is the price of empire. This is the cost of the long war.