Amid the nail-biting by her staff, Clinton was "resolute," the official says. "She thought this was the right course of action for Israel's interest, for regional stability. She felt at the end of the day that would shine through if you could get people focused on the big picture, and that's what she was trying to do."

Clinton's political skills helped, but the official notes that "these are not just political arguments, because we're talking about issues of life and death and existential threats ... it's also about statesmanship and strategy. So she had to be as much a diplomat as politician to be able to grapple with problem at stake."

As Clinton headed for the airport to return to Washington, cease-fire in hand, the official says, "we were not jubilant, we were not really excited."

"Because we recognized that this is a first step; it's fragile, it remains risky; there remain very real underlying problems that need to be dealt with."

"This was not pop-open-the-champagne time. It was job well done, and now let's get to work on the next thing."