Abu Dhabi — This has been a year when America re-embraced diplomacy after a frustrating decade of war, displaying a relentlessly pragmatic approach that recalls the days of such deal-making former secretaries of state as Henry Kissinger and James A. Baker III.

The secret diplomatic machinations have been dizzying, and sometimes disorienting. President Obama and Secretary of State John Kerry have opened doors and created opportunities for settling intractable conflicts. But the administration’s turnabouts, especially in the Middle East, have been so sudden and unsentimental that Machiavelli himself might blush.

The Iran nuclear agreement was the most striking example of the willingness to engage former adversaries. In his speech last weekend to the Saban Forum in Washington, Obama made the case that it’s worth experimenting to see if Iran’s drive toward nuclear weapons can be reversed through diplomacy. He gave his gambit a 50 percent chance of success; given that war is a possible alternative, that’s a reasonable wager.

Israelis I talked to afterward were impressed (if not always convinced) by the dry, precise clarity of Obama’s argument for testing the Iranians. We’ll find out next year if Obama meant it when he said that a bad deal (i.e., one that didn’t make sure the Iranian program remains peaceful for years to come) would be worse than none at all.

What’s fascinating about the Iran effort is how long it had been germinating in the dark. The feelers went out back in 2012 when Hillary Clinton was secretary of state and the fire-breathing Mahmoud Ahmadinejad was president of Iran. A back channel was provided by the sultan of Oman, an eccentric character worthy of a spy novel, who learned the arts of clandestine activity from the masters, the British. These covert contacts accelerated when Hassan Rouhani was elected president last June, but they were blessed first by Supreme Leader Ali Khamenei.

Kerry has even taken on the Rubik’s Cube of diplomacy, the Israeli-Palestinian problem. His argument to both sides, at bottom, has been ruthlessly practical: Begin the transition to Palestinian statehood now, or you’ll regret it later.

Watching the administration’s gyrations on Syria has been less encouraging. Obama shied for more than a year from a serious program to train and arm Syria’s moderate opposition. Had he done the right thing back in mid-2012, the rebels today might have up to 10,000 CIA-trained fighters, who could have prevented al-Qaida from recapturing the Euphrates valley. Now, with the bootless moderate opposition shattered and al-Qaida surging, Obama has decided to work with Saudi Arabia and its Islamic Front, a not-quite-jihadist group eerily reminiscent of the warlords America backed in Afghanistan in the 1980s.

Given the dismal options available, this latest revision of Syria policy makes sense. But it sits uneasily with the other pieces of the administration’s Syria portfolio — its decision to work with Russia to dismantle Syria’s chemical weapons and its support for a Geneva conference in January to plan a political transition (or perhaps, just organize safe zones for humanitarian relief this winter).

“A hasty solution in Syria is just as harmful as doing nothing,” cautions Samir al-Taqi, a Syrian exile who runs a think tank here. He argues that a shattered Syria can be put back together only slowly, region by region. And he warns that President Bashar al-Assad’s Alawite-led army will never suppress al-Qaida: As America learned in Iraq, he notes, the best weapon against the Sunni insurgency fomented by al-Qaida is a Sunni counterinsurgency.

Egypt is another area where I get dizzy trying to follow administration policy. The United States remained supportive of the Muslim Brotherhood government long after most Egyptians had rejected it last summer; after months of waffling, the United States recently seems to have made the “realist” decision to work with Egypt’s friends in Saudi Arabia and the United Arab Emirates to stabilize its economy and, if possible, push it back toward civilian government.

The 2013 realpolitik tour continues here in the oil kingdoms of the Gulf. The Saudis and Emiratis were so upset by Obama’s opening to Iran and dithering on Syria that they threatened a revolt from decades of alliance with America. Though Obama seems more than fed up with hectoring from Saudi Arabia, he again opted for the conciliatory, diplomatic approach. Defense Secretary Chuck Hagel was in Bahrain last weekend reassuring the Gulf Arabs and reminding them just how much the United States spends on their security.

These diplomatic maneuvers haven’t always been pretty to watch. But critics should recognize that this is interests-based foreign policy in its raw form.

— David Ignatius is a columnist for Washington Post Writers Group.