After millions of Egyptians took to the streets to protest the Muslim Brotherhood's Islamic rule, the Egyptian military, under the command of General Abdel Fattah el-Sisi, removed Egyptian President Mohamed Morsi from office Wednesday. In his place, the army's transition plan calls for Chief Justice of the Egyptian Supreme Constitutional Court Adly Mansour to take over until new elections can be held.

According to Egypt's Al Ahram, el-Sisi said the army plan calls for:

1. "Suspending the constitution;

2. Holding early presidential elections. The High Constitutional Court head will be in charge of the country until then;

3. Forming a national coalition government; and

4. Forming a committee to look into amendments of the constitution."

Morsi's whereabouts were not immediately known, but El-Sisi's televised remarks prompted cheers and fireworks throughout Cairo's packed Tahrir Square. El-Sisi was joined by Ahmed El-Tayyeb, the Grand Imam of Al-Azhar University – a bedrock of Sunni theology, and Coptic Orthodox Patriarch Tawadros II. Copts increasingly found themselves under physical and legal attacks during Morsi's year in office. The Constitutional Court, meanwhile has stood in staunch opposition to Morsi in the past and may be in position to develop a more diverse and moderate government focused on Egypt's economic needs.

Morsi was seen as failing in that regard, distracted by attempts to consolidate power for the Muslim Brotherhood and impose religious law on Egypt's 80 million citizens.

Here's what we know about Mansour; born in 1945 and a 1967 graduate from Cairo Law, Mansour was appointed to the high court by Morsi to replace outgoing Chief Justice Maher el-Beheiry. He has served on the court since 1992 but just took over as chief justice on Monday.

In addition to Mansour, the Supreme Constitutional Court has 10 additional justices. As a proactive force in the Egyptian legislative process, the court has the duty to review all legislation for constitutionality and approves or rejects election laws before they go before parliament and the president.

While many Muslim Brotherhood media outlets remain offline and under the control of Egyptian military forces, a Twitter feed speaking for Morsi called the army's action a coup "rejected by all free men who struggled for a civil democratic Egypt."

And a popular Muslim Brotherhood website had this to say:

"Urgent: Conspiracy against legitimacy…A military coup which thwarts the people and returns Egypt to tyranny…Millions respond sit in the squares of Egypt in support of legitimacy...and Ulema (educated Muslim legal scholars) condemn the coup and stress the obligation of supporting the elected President..Figures of the former regime are returning to the scene on the blood of the martyrs of the revolution of January 25..'For, God always prevails in whatever be His purpose: but most people know it not.' (Quran 12:21)"

Similarly, Mohamed El-Betagy, a member of the Brotherhood's ousted Freedom and Justice Party, questioned the legitimacy of the coup and called for a "rejection of the coup with complete peacefulness and adhering to our just position." El-Betagy went on to paint the Muslim Brotherhood as the victim of attack and mob-rule that could have been accomplished through "peaceful democratic mechanisms."

But the Egyptian military's move, and the massive euphoria it generated, marks a stark rejection of Muslim Brotherhood rule and makes the 80-year-old Islamist movement's future unclear. It remains the best organized political group in Egypt and likely will remain viable in some way. But how it reacts to Morsi's ouster may determine whether it retains any political influence.

Frank Spano serves as the Director of National Security Policy for The Investigative Project on Terrorism.