President Obama on Wednesday said he was “deeply concerned” by the Egyptian military’s ouster of President Mohamed Morsi, vowing to review U.S. aid to the North African nation and calling on commanders there to ensure a civilian government is swiftly established in the heart of the Arab Spring.

“We are deeply concerned by the decision of the Egyptian Armed Forces to remove President Morsi and suspend the Egyptian constitution,” Obama said Wednesday evening. “I now call 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 to avoid any arbitrary arrests of President Morsi and his supporters.”

Earlier Wednesday, the Egyptian military overthrew the first democratically elected president of the country, calling for another set of elections and suspending the constitution. At the same time, Morsi dismissed the military decree and urged his supporters not to abide by new rules of law.

The Egyptian military mobilized armored vehicles Wednesday in what could portend a lengthy and violent clash. Military officials also arrested numerous Muslim Brotherhood figures, including the head of the political party and the organization’s chief deputy, drawing questions about how they would operate in the coming days.

The White House had been reluctant to wade too deeply into the explosive clash in Egypt, not wanting to stoke instability in the volatile region or appear resistant to democratic reforms that were instituted just a year ago.

More problematic for the Obama administration is whether to label the developments in Egypt a military coup. If they do, U.S. law would force them to cut off more than $1 billion in aid.

“Given today’s developments, I have also directed the relevant departments and agencies to review the implications under U.S. law for our assistance to the government of Egypt,” Obama said.

Some lawmakers on Wednesday said that although they supported democratic reforms, the United States would have to halt financial support for the North African nation.

“Our law is clear: U.S. aid is cut off when a democratically elected government is deposed by military coup or decree,” said Sen. Pat Leahy, D-Vt.

Before issuing his response, Obama huddled with Defense Secretary Chuck Hagel, CIA Director John Brennan, Joint Chiefs of Staff Chairman Martin Dempsey and Director of National Intelligence James Clapper for several hours at the White House.

Some of Obama’s Republican counterparts welcomed Morsi’s downfall.

“For their part, President Morsi must put the interests of Egypt’s diverse population ahead of the interests of himself or the Muslim Brotherhood,” said House Majority Leader Eric Cantor, R-Va. “The Egyptian people have made clear that President Morsi’s Muslim Brotherhood government has threatened the pluralistic democracy for which they called two years ago. As President Obama has said, democracy is about more than elections.”

Added Republican Chairman of the House Foreign Affairs Committee Ed Royce: “Morsi was an obstacle to the constitutional democracy most Egyptians wanted. I am hopeful that his departure will reopen the path to a better future for Egypt.”

In Morsi, Obama encountered many of the same problems he did with former Egyptian President Hosni Mubarak, a one-time U.S. ally who was unable to recognize the will of his people. The president remained on the sidelines even though frustration with Morsi mushroomed, hoping to avoid another government overhaul so soon after the transition to democracy in Egypt.

And it is not clear which political ideology will dominate leadership posts in the next Egyptian government. In fact, there’s no guarantee that the hardline Muslim Brotherhood, Morsi’s political party, doesn’t assume power again.

“During this uncertain period,” Obama said, “we expect the military to ensure that the rights of all Egyptian men and women are protected, including the right to peaceful assembly, due process, and free and fair trials in civilian courts.”