When Alexander the Great died at the age of 32 in 323 B.C., his once unbeatable army began a 2,900-mile withdrawal from India and headed home to Macedonia. As they retreated, the empire they had created collapsed behind them. To prevent pursuit, Alexander’s royal cavalry and infantry dealt viciously with all internal dissent, destroyed cities and burned bridges. The Russians employed a similar scorched-earth tactic against Napoleon in 1812, as did the Red Army when Nazi Germany invaded the Soviet Union in 1941. It’s a maneuver now being employed both domestically and internationally by Barack Obama.

The re-elect Obama-Biden machine has less sanguinary methods for dealing with discord in the ranks than the Macedonian army used 2,335 years ago. There are no goblets of poisoned wine, no toxic darts — but the Obamians and Bidenites are no less effective. It took just hours for Democrats Cory Booker — mayor of Newark, N.J. — and U.S. Sen. Dianne Feinstein to recant after they had the temerity to criticize our Nobel laureate.

Mayor Booker told NBC’s “Meet the Press” that he was “very uncomfortable” with attacks on Republican Mitt Romney’s tenure at Bain Capital, and he said, “If you look at the totality of Bain Capital’s record, they’ve done a lot to support businesses, to grow businesses.” Less than two hours later, Hizzoner was on Twitter “clarifying” his remarks. Apparently, the social network message wasn’t good enough for the O-Team. That night, in an eerie re-enactment of “purge confessions” filmed by Josef Stalin’s NKVD, Booker went before cameras in a Web video, saying, “I encourage it, for the Obama campaign to examine (Romney’s) record and to discuss it.”

Feinstein, chairwoman of the Senate Select Committee on Intelligence, transgressed last Monday when she was asked about leaks of highly classified national security information. She responded: “I think the White House has to understand that some of this is coming from their ranks.” Less than 24 hours later, the senior Democrat emerged from the White House woodshed to express regret for her words and penitently add, “I know for a fact the president is extremely troubled by these leaks.”

At least Booker and Feinstein know what they did “wrong” and can avoid retribution by simply keeping their mouths shut. And though it may be tough to be a political crony of this president’s, consider a few examples of how dangerous it is to an American ally.

Poland, Romania and the Czech Republic took great risks to base NATO ballistic missile defenses on their territory. The O-Team threw them under the “Russian reset” bus in the first weeks of the administration, when our naive and inexperienced president pulled the plug on the vital project at the insistence of Vladimir Putin.

Canada, America’s No. 1 trading partner, was ready to start building the Keystone XL pipeline to refineries and distribution hubs in the U.S. The project would create thousands of U.S. jobs and provide safe, affordable oil from one of our closest friends. Instead of giving the go-ahead to start construction, the O-Team, pandering to radical environmentalists, put the pipeline on indefinite hold. Unless we hire a new chief executive in November, we could lose the chance for greater energy security and an opportunity to stop funding the jihad with our petrodollars, while our neighbors sell their oil to China instead.

It’s much worse for Mexico, where nearly 50,000 people have been killed in drug-fueled violence since 2006. With narco-terrorism now spreading to neighboring Guatemala and Honduras, the O-Team decided to allow thousands of firearms to flow across the U.S. border to drug cartels in the ill-conceived “Fast and Furious” operation. The result: more dead Mexicans, at least one dead American Border Patrol agent and Attorney General Eric Holder held in contempt of Congress.

Britain, now hosting the 2012 Olympic Games and America’s closest overseas ally for 71 years, also is paying the O-Team price. When Cristina Kirchner, president of Argentina, reasserted her country’s claim to the Falkland Islands on the 30th anniversary of the Falklands War, Obama stated that the United States is “going to remain neutral” in the dispute, despite an overwhelmingly pro-British plebiscite. In 1982, when Argentina invaded the islands, President Ronald Reagan provided U.S. support to the Brits. Now the best our president offers is neutrality.

Israel, our only democratic ally in the Middle East, faces an existential threat from a nuclear-armed Iran. Yet the O-Team continues to badger, bluster and caution against military action and insist on a “diplomatic solution.” The target of all the warnings: not Iran but Israel. Now, with the imminent collapse of the Assad regime in Damascus, the Israelis face the prospect of a radical Islamist takeover in Syria — and thousands of chemical and perhaps biological weapons of mass destruction in the hands of terrorists. The Obama administration urges “all parties to refrain from violence.”

In the Pacific, the People’s Republic of China now asserts control over land and water that the Philippine government claims to be its sovereign territory. The Aquino administration in Manila has been unable to get the O-Team on the phone.

Abandoning friends, burning bridges and embracing enemies didn’t end with Alexander the Great. Jimmy Carter did it oh so well. Obama the Great has made it an art form.