Daniel Byman is a professor in the security studies program at Georgetown University and the research director of the Saban Center for Middle East Policy at the Brookings Institution. Tamara Cofman Wittes is director of the Saban Center. This essay draws upon their contribution to the Brookings publication “Big Bets and Black Swans: A Presidential Briefing Book.”

Egypt’s Muslim Brotherhood is not a terrorist movement, at least not currently. But the move by the military-led government to ban it from politics and declare it a “terrorist organization” may become a self-fulfilling prophecy.

The announcement followed a car bombing outside a government security building in Mansoura on Dec. 24 that killed at least 15 people; the government blamed the Brotherhood. Now, Brotherhood members and donors risk prosecution and imprisonment, and the ban is potentially crippling to the vast network of schools, clinics and other social services the Brotherhood runs and to the poor Egyptians who have long relied on them. Dozens of Brotherhood members have died in recent weeks in street protests, and the movement is reportedly reestablishing a clandestine infrastructure — learning, again, how to survive in the face of a government onslaught.

The crackdown will undoubtedly drive some of the Brotherhood’s members to terrorism. Already, the military ouster of Brotherhood leader and elected president Mohamed Morsi in July has lent strength to al-Qaeda’s long-held view that electoral politics is treacherous and that the Islamist project can be advanced only through violence. The government’s action has thrown together adherents of two streams of Islamism that had opposed one another and has created a new wave of recruits for violent extremism.

Egypt’s path is now clear: It is on the road to even greater repression, strife and instability. The radicalization of the Brotherhood seems more a question of “when,” not “if.” In the name of fighting terrorism, the regime is making the problem far worse.

And what happens in Egypt won’t stay in Egypt. Morsi’s tenure forced the Brotherhood to accede to measures to contain Hamas in Gaza, but the coup gives the Brotherhood incentives to strengthen ties with its terrorist cousins. With Egypt already facing challenges policing the flow of arms and people across its borders, the crackdown could exacerbate extremism in Gaza and across Libya and the rest of North Africa.

Polls show that, by the time of Morsi’s ouster on July 3, he and the Brotherhood were increasingly unpopular. Their lack of progress in improving Egypt’s economy, and their insularity and authoritarianism, alienated many Egyptians. Today, the number of Brotherhood supporters is hard to gauge: Though Morsi won runoff elections with more than 13 million votes, the Brotherhood’s share of the parliamentary vote was closer to 35 percent, and its popularity fell further given its poor performance in power. So a minority of number of Egyptians are committed backers, and an even smaller number are considered members of the organization. But whatever the exact figure, it is clear that millions of Egyptians support the Brotherhood.

Arrests of major Brotherhood leaders followed the coup, and the subsequent crackdown killed more than 1,000 Egyptians. The military regime hopes to crush the Brotherhood, eliminating its leadership and intimidating its followers. Neither U.S. calls for reconciliation nor the Obama administration’s belated October decision to temporarily freeze some forms of aid have had much impact on what most participants see as an existential struggle for the future of Egypt. Saudi Arabia and other gulf allies have provided billions of dollars to the military-led government — far more thanU.S. aid — and promised to make up any shortfall should Washington further cut support. Brotherhood leaders, including the ousted president, are beingput on trial , and there appear to be no prospects for a compromise that might bring Brotherhood elements back into the political system.

The Brotherhood is vaunted for its hierarchy and discipline — and so far, it has not called its members to arms. But this could change as the government further criminalizes the group. In the past, the Brotherhood weathered its exclusion from political power by concentrating on civic activism. This time, however, the regime has banned the Brotherhood outright and seized its assets, denying the movement outlets for members who want to build their vision of an Islamic society.

Given this, Egyptians who supported or joined the Brotherhood may take up arms out of frustration with politics. In the past, jihadi groups often excoriated the Brotherhood for participating in controlled elections and for being insufficiently zealous at home and abroad. Now they cite the coup as proof that America and its local lackeys will not allow their Islamist project to flourish. Islamists in other Arab countries are watching and will draw lessons as well. Thus, one threat of Islamist radicalization in Egypt is the cultivation of a new generation of extremist recruits for the global jihadi cause.

In addition, the imprisonment and prosecution of the senior Brotherhood leadership weaken organizational discipline, particularly to enforce nonviolence. Brotherhood cells might act on their own to vent frustration or to avenge dead comrades, provoking a government response that is likely to perpetuate violence and repression. Some members and supporters have already attacked government targets and Egypt’s Christian population. And existing terrorist groups are probably already working to bring Brotherhood members into their ranks. If even a fraction of the millions of Brotherhood supporters embrace violence, that means tens of thousands of Egyptians are potential recruits for jihadis. The Mansoura bombing was probably carried out by Ansar Bayt al-Maqdis , a Sinai-based terrorist group that does not have formal ties to the Brotherhood and whose ideology is close to that of al-Qaeda. But soon this may be a distinction without much difference.

The situation has implications for the security of Israel and the United States. Terrorism from the Sinai Peninsula has long been a problem, and a surge in resources and fighters from former Brotherhood ranks to Sinai-based groups could lead to more rocket strikes and cross-border raids into Israel. Meanwhile, the United States has never been popular among the Brotherhood’s supporters. While some Egyptians oddly blame Washington for Morsi’s election, many in the Brotherhood believe that the overthrow of Morsi was engineered with Washington’s support. It’s possible that the group’s members might direct their ire toward American targets.

The Egyptian regime is primarily focused right now on securing its hold on power, while America’s interests lie in the stability of Egypt and the region. The United States cannot prevent the radicalization of the Brotherhood, but it can seek to mitigate its effects on U.S. security.

Step one is for U.S. officials to make clear to Egypt’s military leaders that Washington does not think a wholesale turn to violence by the Brotherhood is inevitable. U.S. officials should continue to engage Islamist politicians and opinion leaders who are committed to nonviolence, including such Brotherhood leaders, in Egypt and around the Muslim world. The goals must be to maintain visibility into the movement’s debates and evolution, to press for continued vocal commitments to nonviolence, and to make clear U.S. willingness to deal with Islamists who embrace democratic principles. Those who condone or incite violence should, however, feel swift U.S. condemnation.

Yet Egypt does have a real terrorism problem, and the government’s self-defeating approach to the Muslim Brotherhood should not obscure this. The United States should emphasize to the Egyptian military that it will have America’s support for targeted efforts against radicals who plot against U.S. citizens or U.S. interests, such as the security of Israel — but that Washington does not see all Islamists as terrorists, nor all Islamist threats as having equal priority. The United States should also broaden its intelligence efforts on Islamist radicalization and focus its security engagements with Egypt and other Arab allies on counter-radicalization, not simply counterterrorism.

Finally, the administration should press the Egyptian government to release from prison Islamist politicians who commit to nonviolence and to allow parties with a range of Islamist views to organize and compete in elections.

The Brotherhood might become only a shadow of its former self. But without some peaceful means to participate in shaping their country’s future, the millions of Egyptians who support the Brotherhood may feel no stake in sustaining that future, and some will seek instead to tear it down.

@dbyman