Egypt's most prominent dissident warned in a tweet Thursday night that the country "will explode" and appealed to the army for help.

"Egypt will explode. Army must save the country now," Mohamed ElBaradei, the former head of the nuclear watchdog IAEA, tweeted.

His warning of violence came minutes after President Hosni Mubarak declared in a speech that he would not step down as president until the September elections. Reporters at Cairo's Tahrir Square said the crowds there were angrier than they had seen them since protests broke out on Jan. 25.

Chaos and confusion reigned late Thursday in both Cairo and Washington as observers tried to make sense of Mubarak's refusal to resign following a day of rumors claiming he would do just that.

US intelligence officials admitted that they were as in the dark on Mubarak's plans as anyone else, as evidenced by the fact that earlier in the day CIA director Leon Panetta had declared a "high likelihood" that Mubarak would resign in his speech.

President Barack Obama issued a statement Thursday evening that suggested confusion over Mubarak's motives but growing resolve to push for democracy in Egypt.

"It is not yet clear that this transition is immediate, meaningful or sufficient," Obama said of Mubarak's announcement that he was handing over powers to Vice President Omar Suleiman.

"The Egyptian government must put forward a credible, concrete and unequivocal path toward genuine democracy, and they have not yet seized that opportunity," the president added.

Confusion reigned in Cairo as well, where social media were alive with speculation that Mubarak may be trying to prod protesters into violence. Guests on Al Jazeera speculated that Mubarak may be propagating rumors of his departure in order to anger protesters into violent acts, justifying a military crackdown.

Protesters in Cairo's Tahrir Square were heard yelling "peaceful!" as a rallying cry, suggesting they feared possible military action.

Egypt's amabassador to the US tried to clear up some of the confusion surrounding Mubarak's status following his declaration he was transferring power to Suleiman.

"Mubarak has no power is an interpretation you can make. He is de jour head of state," Sameh Shoukry said.

The ambassador said Suleiman now held all the responsibilities of the office of president, including control of the military.

Suleiman, who headed Egypt's General Intelligence Directorate for 17 years, was appointed by Mubarak to the office of vice president last week.

Human rights activists criticized the move, noting that Suleiman has long been linked to allegations of torture in Egypt's security forces. Suleiman was reportedly the CIA's "point man" in Egypt for the agency's controversial extraordinary rendition program, which saw terrorism suspects flown to countries with lax civil rights laws to be tortured.