CHILMARK, Mass. — Each morning this week, Susan E. Rice has called or come to a secluded contemporary house here, intelligence reports at hand, to brief President Obama about the chaotic world that has followed him on vacation.
On Wednesday, Ms. Rice, the national security adviser, delivered a particularly troubling report: Egypt’s military had begun a bloody operation to clear two camps of demonstrators protesting on behalf of that country’s ousted president, Mohamed Morsi. Among the options she laid out was a plan already on the table to pull the United States from joint military exercises with Egypt.
After Mr. Obama left to play golf, Ms. Rice, 48, returned to her own lodgings to consult with aides at the White House. After 5 p.m., the two spoke again, and Mr. Obama signed off on the plan.
The turmoil in Egypt, which erupted in early July just as she took up her job, has presented the toughest test yet for Ms. Rice, who in six weeks has already dealt with a terrorist scare that prompted the closing of embassies across the Middle East and with the latest chapter in deteriorating relations with Russia: the saga of Edward J. Snowden, a former National Security Agency contractor, which led Mr. Obama to cancel a meeting with President Vladimir V. Putin of Russia.
Given her reputation as an outspoken defender of human rights and advocate of American intervention to prevent abuses, some analysts wondered if Ms. Rice, a former United Nations ambassador, would bring a more muscular, idealistic cast to Mr. Obama’s foreign policy.
Aides said her counsel on Egypt, however, had been resolutely pragmatic: signal America’s displeasure by canceling the military exercises and holding up the delivery of F-16 fighter jets, but avoid rupturing a four-decade relationship with Egypt’s military leaders.
“She has wanted to preserve the relationship,” said a senior administration official, who spoke on condition of anonymity to discuss internal deliberations. “She’s pretty realistic on some of these issues.”
The mere fact that Ms. Rice has traveled to Martha’s Vineyard this week attests to her closeness to the president. She is the first national security adviser to make one of Mr. Obama’s vacation trips, which were staffed in the past by aides like Benjamin J. Rhodes, a deputy national security adviser, and Denis R. McDonough, the chief of staff, whose history with Mr. Obama goes back to the 2008 campaign.
And Ms. Rice is not only working, she is also socializing with Mr. Obama and his wife, Michelle. On Wednesday evening, after briefing him on Egypt, Ms. Rice attended a sunset cocktail party given for the Obamas by the cable TV mogul Brian Roberts, mingling with guests like Attorney General Eric H. Holder Jr.; Valerie Jarrett, a close Obama adviser; and Larry David, who talked about his new HBO movie, set on Martha’s Vineyard.
Ms. Rice, who got to know Mr. Obama as a foreign policy adviser during his campaign in 2008, has brought along her husband, Ian Cameron, a TV producer, and their two children. In between the crises, aides say, she is trying to spend time with her family.
People who know Ms. Rice said she aspires to be not just a confidante and internal broker of policy options for the president — as was the model for previous national security advisers — but also a strategic thinker and a public voice for foreign policy.
If so, Egypt may be a hard policy to sell. The administration’s reluctance to cast off the Egyptian military is exposing it to criticism that it is tolerating a brutal regime with no plans to return Egypt to democracy and no qualms about gunning down its people. Ms. Rice, officials said, will have to judge how much bloodshed the United States can stomach.
It is a familiar quandary. Ms. Rice pushed Mr. Obama to back a NATO intervention against Col. Muammar el-Qaddafi in Libya and has expressed regret, as an official involved in the debate, that the Clinton administration did not do more to prevent the genocide in Rwanda in 1994.
Bruce O. Riedel, a former intelligence official who worked with Ms. Rice during the Clinton years, likened her predicament to that of Zbigniew Brzezinski, the national security adviser to Jimmy Carter, who watched helplessly in 1979 as an Islamic revolution in Iran turned that country away from the United States for decades.
“Obama and Rice are in the same place as Jimmy Carter and Zbig Brzezinski were in 30 years ago,” Mr. Riedel said. “You know that what’s happening is extremely important, but you are a bystander to the big decisions. It’s a really, really tough call because your leverage is minimal.”
Shadows of the past hang over another major issue, the terrorist threat in Yemen, which led the administration, after a series of meetings led by Ms. Rice, to close 19 American embassies and consulates across the Arab world for nearly a week.
Some critics contended that she had overreacted because of her searing experience after the attacks on the American diplomatic mission in Benghazi, Libya, when she was accused of presenting a sanitized account of the episode on Sunday talk shows.
Yemen’s government said closing the embassies had served “the interests of extremists” and undermined its cooperation with the United States on counterterrorism. At home, Fox News characterized Ms. Rice as the driving force behind the decision.
Administration officials said Ms. Rice was reflecting a generally heightened level of caution within the White House because of intelligence suggesting American embassies are a “soft target” for terrorist groups like Al Qaeda in the Arabian Peninsula.
But more broadly, officials said, the administration had learned from Benghazi. For example, it provided extensive briefings to lawmakers, to avoid the kind of criticism that welled up after Benghazi from Senator John McCain, Republican of Arizona, and others.
“You learn lessons from your experience, both in terms of taking every precaution possible, in making sure every element of the government is on a hair trigger, and in making sure Congress is a partner,” Mr. Rhodes said.
Ms. Rice has had bitter experience with vulnerable embassies. She was assistant secretary of state for African affairs when truck bombs simultaneously destroyed the American Embassies in Kenya and Tanzania on Aug. 7, 1998, killing more than 250 people. In the weeks afterward, Ms. Rice traveled to both countries to survey the damage — an experience that friends say left lasting scars.
“Fifteen years ago, the bombing of the embassies in Africa happened on her watch,” Mr. Riedel said. “Because of her background, because of Benghazi, it’s not fair, but it’s going to be an issue for her.”
Ms. Rice’s pragmatism is no surprise to those who worked with her at the United Nations or in the Clinton administration, where she had a previous stint in the National Security Council. But White House officials say they have been struck by her management style, which they call more inclusive than that of her predecessors.
When the White House was deliberating whether Mr. Obama should cancel a meeting with Mr. Putin after Russia granted asylum to Mr. Snowden, Ms. Rice brought Michael A. McFaul, the ambassador to Moscow, into the debate among top officials. Mr. McFaul argued that the president should not go.
“Susan deserves credit for leading the U.S. government to make such a hard, and correct, decision,” he said.
