UPDATED July 5 at 9:15 a.m.
The Muslim Brotherhood called Friday for protests across Egypt, a day after President Mohammed Morsi was arrested and a new president was sworn in, the Associated Press reported. And in the Sinai Peninsula, Islamic militants angry over Morsi's ouster attacked military and police posts, leading to an exchange of fire.
The twin developments raised concerns that this week's military-backed regime change in the Middle East's most populous country could trigger violent reprisals from the Brotherhood and its supporters, according to the AP.
The chief justice of Egypt's high court was sworn in as the country's interim head of state on Thursday just hours after the military seized power and removed the country's first democratically elected president, arrested him and suspended the constitution.
In a short, televised swearing-in ceremony, Adly Mansour, chairman of the Supreme Constitutional Court, pledged new elections and praised the hundreds of thousands of protesters who had gathered in Cairo's Tahrir Square for days calling for the ouster of the Muslim Brotherhood-backed Mohammed Morsi.
Morsi, along with members of his presidential team, was placed under house arrest, a senior adviser to the Freedom and Justice Party and spokesman for the Muslim Brotherhood confirmed. An Egyptian prosecutor has also called for the arrest of eight senior Muslim Brotherhood leaders for defaming the judiciary, NBC News reports. They have been barred from any travel outside the country.
Even as a crackdown on Morsi's Islamist supporters ensued, Mansour used his inauguration to reach out to the Muslim Brotherhood in charting a path forward for Egypt. The movement is "part of this people and are invited to participate in building the nation as nobody will be excluded, and if they respond to the invitation, they will be welcomed," Reuters reported.
Armored vehicles, tanks and troops advanced along the outskirts of Cairo as the Egyptian military executed a coup, forcing an end to a year-long presidency that came about after decades of dictatorial rule by Hosni Mubarak. When the commanding general, Abdul Fatah Khalil Al-Sisi announced that the transition was complete, and Morsi was out late Wednesday, the crowds in Tahrir Square responded with roars, applause, and fireworks marking an end to what had become an unruly regime.
Egypt, long a central U.S. ally in the Middle East, is the largest and most important Arab country. Although it did not seed the Arab Spring, the fact that Egyptians became such a key part of the movement that began in Tunisia, gave rise to other protests and calls for freedom across the Middle East.
The initial change in power, which brought Morsi to the presidency, was an early test for the Obama administration and how it would respond to calls for democracy that also meant the exit of strategic partnerships begun decades earlier. Just a day earlier, the Obama administration was cautious in its response to demonstrations calling for Morsi's ouster and strongly denied that it was pushing for early elections.
President Obama issued a statement that said in part, "The United States is monitoring the very fluid situation in Egypt, and we believe that ultimately the future of Egypt can only be determined by the Egyptian people." He called on the Egyptian military "to move quickly and responsibly to return full authority back to a democratically elected civilian government as soon as possible through an inclusive and transparent process." And he concluded by saying that "the longstanding partnership between the United States and Egypt is based on shared interests and values, and we will continue to work with the Egyptian people to ensure that Egypt's transition to democracy succeeds."
The president said he would order an assessment of what the military's actions meant for U.S. foreign aid to Egypt. U.S. law says the government must suspend foreign aid to any nation whose elected leader is ousted in a coup d'etat. The U.S. provides $1.5 billion a year in military and economic assistance to Egypt, a key U.S. national security priority.
Following the coup, State Department officials ordered all non-essential U.S. embassy staff and families to leave Egypt as soon as possible and to avoid all demonstrations, even seemingly peaceful protests.
Egyptians, new to the democratic process, quickly grew weary of Morsi's Muslim Brotherhood, a party founded on Islamic faith in a largely secular state that had never been run by religious rule. Further unrest boiled over for the almost 83 million people living in Egypt as Morsi's rule failed to bring on the economic stability they had hoped for and expected.
“This was an experiment in political Islam that many in Egypt say went terribly wrong," NBC News' Richard Engel reported from Tahrir Square. "They didn’t have the institutions to impeach him—there were not the political structures in place to do anything else to remove him."
Tensions culminated on Monday when the military issued a 48-hour ultimatum for Morsi to step down and allow new elections following an "unprecedented" display of public support for his ouster—the government estimates that least 16 people have been killed, and another 200 injured in the demonstrations.
Morsi rejected the military's calls in a speech televised overnight Tuesday, and passionately defended his right to rule, focusing on his ascension to power through a democratic election. "If the price of preserving legitimacy is my blood, I am prepared to pay it," he said.
Both sides sparred with competing statements posted onto Facebook—the social media site that sparked the beginnings of the initial Arab Spring uprisings—as the deadline came and went Wednesday afternoon, local time. Armored vehicles, tanks and troops soon advanced along the outskirts of the capital as cheers of jubilation rang out in the square.
With the military takeover, Egypt now enters uncertain political territory, creating renewed instability in the Middle East as conflicts rage in nearby Syria, and the United States attempts reconciliation among Israelis and Palestinians.
Sisi had been appointed by Morsi but the relationship did not help to ease tensions and suspicions between the military and the Muslim Brotherhood.
The general and advisers met earlier in the day with Mohamed Elbaradei, the former head of the U.N. Nuclear Agency who returned to Egypt last year and worked hard to ferment democratic change in his native country. Elbaradei knows Obama and many world leaders personally from his work at the U.N. and has served as both a sounding board and mediator during the last tumultuous year of political change.