WASHINGTON - For John Kerry, vindication came at midnight.

As last Monday became Tuesday in Vienna, the U.S. secretary of state picked up the telephone in his first-floor room at the ornate, 19th-century Palais Coburg and dialed the White House.

We have a deal, Kerry told President Barack Obama.

After nearly 18 days of intense, often fractious and highly technical negotiations in the Austrian capital, he reported an agreement to curb Iran's nuclear program in exchange for sanctions relief. All that remained was cleaning up the written details, Kerry said, a task that would be completed in the wee hours of Tuesday morning. Then, world powers and Iran would announce the accord to the world.

The call to Washington was a capstone to the kind of bold gamble that Kerry has relished since becoming America's top diplomat in 2013.

There was no applause, backslapping or celebratory toasts, according to American officials who recounted the moment on condition they not be identified by name. Instead, there was relief accompanied by sober recognition of months of hard work ahead to convince skeptical, perhaps inconvincible, lawmakers to support the deal, as well as wary U.S. allies in Israel and the Arab world.

Given some of the virulent opposition already to the deal, Kerry's restraint may prove prescient. Talk of unqualified success or Nobel Peace Prize for the July 14 accomplishment may be premature.

Almost two years to the day earlier, on July 19, 2013, Kerry bounded onto his converted Air Force 757 in Amman, Jordan, to a standing ovation from staffers after announcing that Israel and the Palestinians had agreed to resume long-stalled peace talks. The goal, Kerry told reporters aboard his plane while sipping a Sam Adams beer, was a comprehensive settlement to the Israeli-Palestinian conflict in nine months. He acknowledged the long odds, but insisted: Yes, it can be done.

At that point, Kerry already had devoted six months just to getting the reluctant sides to return to the table. He would spend eight more months almost single-mindedly pursuing the goal before talks collapsed amid mutual U.S.-Israeli-Palestinian recriminations in what he would later call a bitterly disappointing "poof" moment.

Derided by many as naive and unrealistic from the moment he began his Israeli-Palestinian peace quest, Kerry refused to quit. He was subjected to unusually harsh personal attacks from senior Israeli officials who described him as "messianic" and determined to become a Nobel laureate at Israel's expense. But he persevered until it was more than certain the cause was lost.

By then, the failed 2004 presidential candidate was dealing with world crises on multiple fronts - with decidedly mixed results.

His efforts to resolve the conflict in Ukraine after Russia's annexation of Crimea in March 2014 proved futile. Peace remains elusive.

Syria's civil war deteriorated further despite a deal Kerry brokered with Russian Foreign Minister Sergey Lavrov in mid-September 2013 to remove Syria's declared chemical weapons stockpiles.

That same month, Kerry personally plunged into the Iran negotiations, taking the reins of what had been months of secret diplomacy by subordinates.

On Sept. 26, 2013, he met one-on-one at the United Nations with Iranian Foreign Minister Mohammad Javad Zarif. It was the first private encounter between the top diplomats of Iran and the U.S. in more than 30 years and set the stage for the completion two months later of an interim nuclear agreement. It also marked the beginning of an extraordinary 21-month period that saw high-level U.S.-Iran meetings in cities around North America, Europe and the Middle East become routine.

Just as in the failed Israeli-Palestinian talks, Kerry repeatedly warned that the Iran negotiations could and would not be "open-ended." As the last round of talks blew through three self-imposed deadlines, Kerry showed impatience, at one point getting into a shouting match with Zarif over the future agreement's presentation. Twice in Vienna, Kerry publicly threatened to walk away before the deal was sealed.

At the final meeting of negotiators in Vienna, U.S. officials said, Kerry delivered an emotional address.