The tens of thousands of protesters are trying to bring down the man who has held power in Egypt for 30 years, President Hosni Mubarak. They want better living conditions.
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"If the Egyptian government falls, then all bets are off throughout the region," said David Bender, an analyst with the Eurasia Group.
"Whatever government comes next is likely to be more suspicious, if not outright hostile, but certainly more suspicious of the U.S. than the current regime," Bender said.
Today, President Obama reiterated his support for the Egyptian government, but urged peaceful reform.
"Egypt's been an ally of ours on a lot of critical issues," Obama said at a YouTube town hall. "President Mubarak has been very helpful on a range of tough issues in the Middle East. But I've always said to him that making sure that they are moving forward on reform -- political reform, economic reform -- is absolutely critical to the long-term well being of Egypt.
"My main hope right now is that violence is not the answer in solving these problems in Egypt," Obama said. "So the government has to be careful about not resorting to violence, and the people on the streets have to be careful about not resorting to violence."
State Department spokesman P.J. Crowley also gently urged government reform.
"We want to see political, economic and social reform that opens up the opportunity for Egyptian people, just as the people of other countries, to more significantly influence who will lead their country in the future and the direction of that country and the opportunities generated in that country," Crowley said Thursday.
The United States is not only worried about Egypt as the chorus of discontent spreads. Now, it's crossed the water and the deserts to Yemen, where today thousands of protesters were calling for their president to step down.
"Yemen presents one of the most difficult policy problems for the U.S. right now," Bender said. "On one hand, the regime is a strong ally of U.S. in the fight against terrorism. ... For the U.S., ensuring Yemeni stability is one of the most important policy goals going forward."
Yemen is a growing training ground for al Qaeda and is the home of Anwar al-Alawki, the man considered every bit as dangerous -- if not more -- than Osama bin Laden. He helped the failed Christmas Day bomber, inspired the Times Square bomber, and has called for more attacks on Americans. Bombs discovered on board cargo planes last October also came from Yemen.
Yemeni troops are going after al Qaeda, but that is at risk if the government is overthrown in the poverty stricken nation.
"The fear is that the Yemeni government collapses and suddenly Yemen becomes an absolute mess," Bender said.
"It's a place with little political order once the central government were to fall," Bender said. "You have AQAP [al-Qaeda in the Arabian Peninsula]. You have a complex tribal structure, rebels in the north, secessionsists in the south.
"I think the fear is that this would simply fall apart and, of course, you have Somalia right across the water," Bender added. "And the idea of having two chaotic states in the same place makes policy makers rightly very nervous."
ABC News' Richard Coolidge and Sunlen Miller contributed to this report.