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 […]