RIYADH, Saudi Arabia — Prince Mohammed bin Nayef, the interior minister of Saudi Arabia, arrived at a meeting of security chiefs from across the Arab world in Marrakesh, Morocco, last March to deliver a call to arms: It was time, he declared, for a concerted effort to eradicate the Muslim Brotherhood, according to two Arab officials briefed on the meeting.
Several were stunned at his audacity. Brotherhood-style Islamists are an accepted part of politics in much of the Arab world, including Tunisia, Libya, Jordan, Kuwait, Bahrain and Morocco itself, to say nothing of their warm welcome in Qatar, said the officials, who spoke on the condition of anonymity so as not to anger the powerful Saudi prince.
But this toughness toward perceived enemies to his family’s dynasty is characteristic of Mr. Bin Nayef, a central player in the often opaque leadership of the kingdom who was named last week as deputy crown prince, making him second in line to the throne. Analysts and diplomats who know him say Mr. Bin Nayef embodies Saudi Arabia’s shift to a more assertive foreign policy propping up allies and dismantling perceived foes. Inside the kingdom, he has been a driving force in defeating extremist networks, and in stifling and punishing political dissent.
As world dignitaries including President Obama fly here this week to congratulate the new monarch, King Salman, it is Mr. Bin Nayef’s appointment to deputy crown prince that has captured attention across the Middle East. Analysts and diplomats say his elevation is a harbinger of the Saudi leadership’s longer-term vision for their state and the region, but also raises thorny questions about royal politics among the hundreds of princes who may feel passed over.
Mr. Bin Nayef’s rise in prominence comes amid newly tense relations between Riyadh and Washington, and while his focus on counterterrorism is in line with the White House’s, it is uncertain that he would be any less hostile to the continuing negotiations between Washington and Iran over its nuclear program, or to signals that the White House is no longer pushing for the ouster of Syria’s president, Bashar al Assad.
At the same time, Mr. Bin Nayef’s security-first approach to preserving stability and silencing political opposition has been criticized by human rights groups and has often been cited as a motivation by those who support radical Islamist groups.
“He is the architect of crackdown on and jailing of these activists with ludicrously harsh sentences,” Mr. Coogle said. “This is all on his watch.”
Still, after a recent attack on members of Saudi Arabia’s Shiite minority in its eastern province, Mr. Bin Nayef flew to the funeral to pay his respects — an important gesture for a Saudi royal.
In 2009, Mr. Bin Nayef was lightly wounded when a militant who came to his palace saying he wanted reform blew up a bomb hidden in a body cavity. Though some criticized Mr. Bin Nayef for letting his guard down, Mr. Alani, of the Gulf Research Center, said that Mr. Bin Nayef had told his guard not to search the man so as not to humiliate him.
“It showed that this man is not delegating things to his assistants,” Mr. Alani said.
A version of this article appears in print on January 27, 2015, on page A1 of the New York edition with the headline: Saudi Succession Hinting at Shift in Foreign Role. Order Reprints| Today’s Paper|Subscribe