A hooded police officer prevents media from aproaching the scene of a bus explosion in the center of the capital, Tunis, Tunisia, Tuesday, Nov. 24, 2015.

A hooded police officer prevents media from aproaching the scene of a bus explosion in the center of the capital, Tunis, Tunisia, Tuesday, Nov. 24, 2015. AP Photo/Hassene Dridi

Darkness in the Arab Spring’s Brightest Spot

Tunisia declared a state of emergency on Tuesday after an explosion killed 12 presidential guards in the capital.

Last month, the Norwegian Nobel Committee bestowed the world’s most prestigious prize upon The Quartet, a body consisting of four Tunisian groups, whose work helped ensure a peaceful democratic transition in Tunisia in 2013.

In its statement, the Nobel Committee paid homage to Tunisia’s successes in the aftermath of the Jasmine Revolution, but also acknowledged that the country still “faces significant political, economic, and security challenges.”

Related: As Jihadis Gather in Libya, Tunisia Struggles To Fend Them Off

As Tunisia tries to endure as the birthplace of the Arab Spring and its golden child, violence keeps interrupting. Back in March, 23 people died in a terrorist attack at the Bardo Museum in the capital city of Tunis and, in July, 38 tourists were killed when a gunman opened fire at a beach in Sousse. Both attacks were claimed by the Islamic State.

On Tuesday, not far from the Bardo Museum, an explosion killed a dozen Tunisian presidential guards and wounded several others on a bus in the central part of the capital. No group has claimed responsibility yet, but following the attack, President Beji Caid Essebsi reinstated the country’s state of emergency, which had been lifted in October, and set a curfew. The violence comes just one week after Tunisia’s interior ministry boasted that security forces had foiled a major plot against a number of targets when it broke up a heavily armed terrorist cell in the country.

As the Islamic State’s ranks swelled last year, the small North African country also produced the biggest number of foreign fighters in Syria and Iraq. Western analysts still believe that the country’s border towns are a crucial haven for ISIS recruitment.

Tuesday’s attack, especially if claimed by ISIS, doesn’t just undermine Tunisia’s security. It also weakens the model to which other Middle Eastern countries can aspire. Christian Caryl made this case earlier this week for Foreign Policy:

If Tunisia can maintain and expand its democratic institutions, it will send a vital message to the rest of the Middle East and North Africa. It will show that Arabs and democracy don’t have to be mutually exclusive. It will show religious Muslims that they have nothing to fear from the separation of religion and state. And it will show liberals that they don’t have to tolerate corrupt dictators as their only protection against religious dictatorships. A prosperous and vibrant Tunisian democracy is our best counter-argument to jihadist dictatorship.

Following the latest attack, there were still some promising notes. By Tuesday night, Ennahda, the country’s leading Islamist party, issued a statement that called for unity and denounced the assault.

“Tunisia is targeted because it is a democracy and represents a model of moderate Islam,” the party said.