President Barack Obama is channeling George W. Bush in launching a new Mideast war. Why is Washington involved?

The Islamic State is evil, but the organization’s raison d’etre is establishing a Middle Eastern caliphate, or quasi-state, not terrorizing Americans. In fact, grabbing territory provided the U.S. with a target for retaliation in response to any attack, something lacking with al-Qaida.

The murder of Americans and Britons captured in the region was horrid but opportunistic. Morally abominable, yes. Cause for war, no.

Washington has never had much success in fixing the Middle East. The U.S. has been bombing Iraq since 1991. The Islamic State would not exist but for America’s 2003 invasion. Saddam Hussein is dead, but so are more than 200,000 Iraqi civilians.

Washington has been battling al-Qaida since 2001. While the national organization is largely kaput, the group has spawned multiple national off-shoots.

The Bush administration justifiably overthrew the Afghan Taliban as punishment for hosting al-Qaida. But 13 years of nation-building has been far less successful.

Three years ago, the Obama administration declared that Syria’s Bashar al-Assad had to go, discouraging rebel forces from negotiating with him. Since then “moderates” have lost ground. The Islamic State’s capture of the city of Raqqa created a base for attacking Iraq.

Washington joined European states in ousting Libya’s Moammar Gadhafi in the name of the Arab Spring. Today the country is in collapse. Yemen, the subject of a lengthy and heavy drone campaign, appears headed in a similar direction.

Now Washington plans to rid the world of the Islamic State.

Alas, targeting the “caliphate” removes the most important deterrent to the Islamic State attempting to stage terrorist attacks in the U.S. If the militants find their conventional ambitions frustrated by Washington, the group might switch direction and cooperate with groups such as al-Qaida. In fact, the al-Qaida-linked al-Nusra Front called on jihadists worldwide to strike at Washington and its allies in retaliation for their “war against Islam.”

The administration almost certainly will be drawn ever deeper into the conflict. Pinprick aerial bombing won’t wipe out adherents of the Islamic State.

U.S. policy in Syria, the scene of the Islamic State’s initial success, is bound to fail. Washington had no reason to join the tragic imbroglio. Assad is a thug, but poses no threat to America, in contrast to the Islamic State.

The administration intends to step up efforts to train and arm the “moderates,” some of whom cooperate with the Islamic State. The likelihood of these groups defeating both Assad and Islamic State is small. While U.S. bombing will hamper the latter’s efforts, the group has been adapting and advancing. The administration could end up helping the insurgents plant their flag in Damascus.

The administration’s campaign is particularly misguided because there are so many other candidates to take on the Islamic State. The organization is essentially at war with every major country in the Middle East.

Its territorial claims directly threaten Iraq, Syria, Jordan, Turkey and Lebanon, as well as autonomous Kurdistan. The group’s stance as self-proclaimed Sunni guardian challenges Iran and Israel. The Islamic State’s Sunni radicalism targets Saudi Arabia and the smaller Gulf kingdoms, as well as assorted Islamist and secular insurgents in Syria. European nations created many of the region’s artificial borders which have generated much strife and birthed many of the radical outsiders who flocked to the Islamic State to do violent “jihad.”

No doubt, Washington’s allies prefer that the world’s superpower take care of the problem. But they obviously are capable of acting. Since its spectacular summer successes, the Islamic State has lost momentum and the element of surprise.

The anti-Islamic State coalition is divided and fractious. But necessity tends to force official compromise and unofficial cooperation.

However, the U.S. is determined again to “lead.” Other countries will help out a little, but most coalition members are likely to do only as much as they believe necessary to limit Washington’s kvetching.

America should leave the Islamic State to its neighbors. Only local governments can create stability. They must adopt economic and political reforms to satisfy discontented publics, nurture popular loyalties to thwart triumphal ideological and theological movements, and employ competent militaries to suppress security threats.

Obviously, such a regional effort will take time. But administration officials are saying the same for the U.S.-led campaign. Plan on years more of war to defeat an enemy that has not seriously threatened America.

Washington has made a hash of the Mideast. But President Obama is continuing Washington’s policy of endless war in the Middle East. As Yogi Berra said, it’s “déjà vu all over again.”