WASHINGTON » Right after President Barack Obama announced the resignation of Defense Secretary Chuck Hagel at the White House on Monday, he walked over to a meeting of his entire National Security Council staff, where he told the embattled group that they were critical to an ambitious foreign policy agenda.

The timing was a coincidence, but it seemed an unmistakable sign that Hagel’s departure does not portend a broader internal shake-up. If anything, it may represent the final triumph of a White House-centric approach to national security.

Obama does not appear likely to replace his national security adviser, Susan E. Rice, who skirmished with Hagel over Syria policy and others. Nor is he mulling a change in his chief of staff, Denis R. McDonough, who has exerted heavy influence over foreign policy, at times acting almost as a shadow national security adviser.

With his core team intact, and with none of the candidates to succeed Hagel likely to show the independence of Obama’s first defense secretary, Robert M. Gates, the White House seems likely to keep a tight leash on foreign policy for the remainder of Obama’s presidency.

The multiple challenges facing Obama’s national security team were emphasized not just by Hagel’s departure but also by the failure of American negotiators in Vienna to strike a nuclear deal with Iran. While experts said the seven-month extension agreed to for the talks was an acceptable fallback that will preserve the chance for eventual success, it suggested how hard it would be to secure a deal that Obama and his aides have long hoped would be a legacy achievement.

The Iran talks, however, have strengthened the standing of another crucial member of Obama’s war council, Secretary of State John Kerry. Kerry will play a central role in trying to negotiate an Iran deal, officials said. In recent weeks, as rumors of a staff shake-up circulated, White House officials emphasized the president’s confidence in Kerry, even as they were more guarded about Hagel.

Still, even in diplomacy, the White House will continue to keep close tabs. Obama, officials say, is relying heavily on McDonough, Rice and other longtime aides like Benjamin J. Rhodes, the deputy national security adviser. The White House was in constant contact with Kerry in recent days, officials said, as he and other foreign ministers worked out the seven-month extension with Iran.

The president recently nominated one of his top aides, Antony J. Blinken, as deputy secretary of state, passing over Kerry’s preferred candidate, Wendy R. Sherman. Kerry had argued that Sherman, the department’s No. 3 official and the lead, day-to-day negotiator on the Iran talks, deserved the promotion. But Obama went with Blinken, who serves as Rice’s principal deputy on the National Security Council.

Some critics say a genuine shake-up would have included Rice, whose sharp manner has alienated members of the council staff and made the internal policy process more contentious. But Obama, aides say, is intensely loyal to her and sensitive to the fact that she was tripped up by the Benghazi episode, when her erroneous statements on Sunday talk shows helped cost her a shot at being secretary of state.

While congressional aides have questioned McDonough’s personal involvement in negotiating over redactions in a Senate report on the CIA’s detention and interrogation policies after the Sept. 11 terrorist attacks, there is no evidence it troubles Obama.

"Not only does the Hagel ouster not address the internal problems in the White House, but it’s also essentially a denial that the problem goes deeper," said David Rothkopf, an expert on the National Security Council who just published a book, "National Insecurity."

Fissures between Hagel and the White House first became apparent in late October when he wrote a memo to Rice sharply criticizing the administration’s policy in Syria. The policy, he said, failed to link the tactical campaign against the Islamic State to the broader strategic question of what do about President Bashar Assad.

As a result, Hagel wrote, the United States was struggling to sign up allies like Turkey and even France for the campaign. He also predicted a difficult situation when Syrian rebels trained and equipped by the United States came under fire from Assad’s forces.

Administration officials insist that Hagel did not advocate this position in internal debates, and indeed, was more reticent on American engagement in Syria than other officials, including Kerry and the U.N. ambassador, Samantha Power.

Hagel’s problems, these officials said, were not rooted in White House micromanagement but in his own discomfort with the nature of the job. The memo on Syria policy, some note, surfaced around the time that Hagel began discussing his future with the president.

Obama, who had appeared on his heels for months in foreign policy, got a lift from his recent weeklong trip to Asia, where he made deals on climate change and trade with China. He also delivered a warning to Myanmar to stay on the reform track, and extolled the American economic recovery at the Group of 20 meeting in Australia.

White House officials credit Kerry with conceiving the climate change agreement after a trip to Beijing in February. He pushed the idea when he hosted China’s senior foreign-policy official, Yang Jiechi, during a visit to his hometown, Boston.

"The president might at times be overwhelmed by Kerry’s enthusiasm," said Martin S. Indyk, director of the Foreign Policy Program at Brookings, who worked with Kerry to try to broker an Israeli-Palestinian peace deal, "but his unflagging energy, his passionate conviction, and his unusual willingness to take risks stand in contrast to Hagel’s more laid-back approach and make him a valued member of the team."

But Obama’s remarks to the close to 400 staff members of the security council underscore that they will remain at the heart of his efforts to manage the world’s crises and recapture momentum in foreign policy, in what White House officials refer to as "the fourth quarter" of his presidency.

"The president’s message was that there’s a very full inbox, but that we have the ability to chart our own course, and make our own agenda, even with all this incoming," said a senior official, who spoke on condition of anonymity to describe the meeting.

Mark Landler, New York Times

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