Egypt’s president, Mohamed Morsi, proved the power of his might Sunday with a shakeup both rumored and surprising to many—sacking the head of the military, Egypt’s de facto ruler throughout the transition period, and several other key members of the distrusted Supreme Council of the Armed Forces.

Morsi resolved to scrap a constitutional document that handed sweeping powers and autonomy to Egypt's military and ordered the retirement of Hussein Tantawi, defense minister and commander of the armed forces, and Chief of Staff Sami Anan, awarding both men state medals and appointing them presidential advisers. He also made his highly anticipated selection of vice president, naming Senior Judge Mahmoud Mekki as his deputy.

While many saw the expanding powers of the military as an attempt to hijack the revolution, the shuffle comes amid a violent standoff with militants on the Sinai Peninsula near the border with Gaza, and an overall lapse in security nationwide. Morsi, a member of the Muslim Brotherhood and Egypt’s first civilian president, was viewed by many as nothing more than a figurehead, since measures taken by the military left little room for a second-in-charge. This latest move leaves many observers questioning whether Morsi’s ability to seize authority had been underestimated.

“This is a palace coup and a very risky one,” said Paul Sullivan, a North Africa expert at National Defense University. “Firing most of the SCAF is a bold move that could backfire at Morsi. He has been losing credibility with the Egyptian public since his election. The Sinai attack was seen by many in Egypt as a sign of Morsi's weakness, not the military and intelligence people. Now he is trying to turn the tables on them.”

The military, which had presided over state affairs since Hosni Mubarak’s resignation in February 2011, had suffered a severe decline in public opinion following a number of violent clashes with protesters that provoked a bitter outcry. An 11th-hour court decision ahead of the presidential election dissolved the country’s Islamist-dominated parliament, leaving Morsi with no new constitution and no legislature when he assumed office on June 30. The decree also left much of the country’s budget—specifically its defense budget—under the autonomous control of the military council. The rulings sparked fury among citizens, who took to Tahrir Square once again, accusing the military of a soft coup.

It has yet to be determined whether Morsi will opt to reinstate parliament following these latest changes; however, with the military council vitiated and parliament annulled, power is predominantly in his hands, further raising concerns among those fearful of an Islamist-dominated government. While Morsi may still name another vice president, the selection of Mekki also is sparking criticism, since one of Morsi’s initial promises after clinching victory was to name a woman and Christian vice president.

Since the popular uprising began in Egypt last year, much of the country has experienced a lapse in law and order, with incidents ranging from assaults on women and sectarian clashes to extremist activities in some outer-lying regions. Tensions in Sinai, long neglected by the Mubarak regime, have escalated significantly in recent days after suspected militants stormed border posts, killing 16 Egyptian solders—and prompting a major military offensive. At least seven militants were killed in clashes with security forces in the Sinai on Sunday, according to the Associated Press.

Morsi also named Abdul Fatah Khalil al-Sisi head of military intelligence days after firing the former chief of the mukhabarat (intelligence) and the governor of North Sinai for the security lapse following Israel’s warning of an imminent plot against border security. The purge marked a bold effort by the Islamist leader to abate widespread anger over the attack.

“Sinai was critical. If it didn’t happen, Morsi wouldn’t have made these changes so soon,” said Shadi Hamid, director of research at the Brookings Doha Center. “Sinai presented a window of opportunity for Morsi. He already shuffled the decks with the mukhabarat head and governor of Sinai, and the failure in Sinai highlighted a number of internal problems, especially with regard to SCAF’s competence.”

But Morsi’s competence is also very much in question by the Egyptian populace. He made numerous promises for his first 100 days in office—a target many presumed to be over in this month. However, the Muslim Brotherhood’s Freedom and Justice Party dismissed criticism of Morsi’s failed promises, claiming that the 100 days began in early August with the selection of the cabinet.

Among Morsi’s promises were vows to address issues ranging from abhorrent traffic problems and sanitation backups to calls for better wages.

The “Morsimeter”—an interactive website created by unidentified activists to monitor Morsi’s 100-day promises—reports that as of Sunday, seven out of 63 presidential promises are in the process of being carried out, and one mandate has been implemented.