   CAIRO — Gunmen opened fire on visitors at Tunisia’s most renowned museum
   on Wednesday, killing at least 19 people, including 17 foreigners, in an
   assault that threatened to upset the fragile stability of a country seen
   as the lone success of the Arab Spring.

   It was the most deadly terrorist attack in the North African nation in
   more than a decade. Although no group claimed responsibility, the
   bloodshed raised fears that militants linked to the Islamic State were
   expanding their operations.

   The attackers, clad in military uniforms, stormed the Bardo National
   Museum on Wednesday afternoon, seizing and gunning down foreign tourists
   before security forces raided the building to end the siege. The museum is
   a major tourist draw and is near the heavily guarded national parliament
   in downtown Tunis.

   Tunisian Prime Minister Habib Essid said that in addition to the slain
   foreigners — from Italy, Poland, Germany and Spain — a local museum worker
   and a security official were killed. Two gunmen died, and three others may
   have escaped, officials said. About 50 other people were wounded,
   according to local news reports.

   “Our nation is in danger,” Essid declared in a televised address Wednesday
   evening. He vowed that the country would be “merciless” in defending
   itself.

   [Read: Why Tunisia, Arab Spring’s sole success story, suffers from
   Islamist violence]

   Tunisia, a mostly Muslim nation of about 11 million people, was governed
   for decades by autocrats who imposed secularism. Its sun-drenched
   Mediterranean beaches drew thousands of bikini-clad tourists, and its
   governments promoted education and other rights for women. But the country
   has grappled with rising Islamist militancy since a popular uprising
   overthrew its dictator four years ago, setting the stage for the Arab
   Spring revolts across the region.

   Thousands of Tunisians have flocked to join jihadist groups in Syria,
   including the Islamic State, making the country one of the major sources
   of foreign fighters in the conflict. Tunisian security forces have also
   fought increasing gunbattles with jihadists at home.

   Despite this, the country has been hailed as a model of democratic
   transition as other governments that came to power after the Arab Spring
   collapsed, often in bloody confrontations. But the attack Wednesday — on a
   national landmark that showcases Tunisia’s rich heritage — could heighten
   tensions in a nation that has become deeply divided between pro- and
   anti-Islamist political factions.

   Many Tunisians accuse the country’s political Islamists, who held power
   from 2011 to 2013, of having been slow to respond to the growing danger of
   terrorism. Islamist politicians have acknowledged that they did not
   realize the threat that would develop when radical Muslims, who had been
   repressed under authoritarian regimes, won the freedom to preach freely in
   mosques.

   In Washington, White House press secretary Josh Earnest condemned the
   attack and said the U.S. government was willing to assist Tunisian
   authorities in the investigation.

   Gunmen in military uniforms stormed Tunisia's national museum, killing at
   least 19 people, most of them foreign tourists. (Reuters)

   “This attack today is meant to threaten authorities, to frighten tourists
   and to negatively affect the economy,” said Lotfi Azzouz, Tunisia country
   director for Amnesty International, a London-based rights group.

   Tourism is critical to Tunisia’s economy, accounting for 15 percent of its
   gross domestic product in 2013, according to the World Travel and Tourism
   Council, an industry body. The Bardo museum hosts one of the world’s most
   outstanding collections of Roman mosaics and is popular with tourists and
   Tunisians alike.

   [Bardo museum houses amazing Roman treasures]

   The attack is “also aimed at the country’s security and stability during
   the transition period,” Azzouz said. “And it could have political
   repercussions — like the curtailing of human rights, or even less
   government transparency if there’s fear of further attacks.”

   The attack raised concerns that the government, led by secularists, would
   be pressured to stage a wider crackdown on Islamists of all stripes.
   Lawmakers are drafting an anti-terrorism bill to give security forces
   additional tools to fight militants.

   [Read: Tunisia sends most foreign fighters to Islamic State in Syria]

   “We must pay attention to what is written” in that law, Azzouz said.
   “There is worry the government will use the attack to justify some
   draconian measures.”

   Tunisian Islamists and secular forces have worked together — often
   reluctantly — to defuse the country’s political crises in the years since
   the revolt.

   Last fall, Tunisians elected a secular-minded president and parliament
   dominated by liberal forces after souring on Islamist-led rule. In 2011,
   voters had elected a government led by the Ennahda party — a movement
   similar to Egypt’s Islamist Muslim Brotherhood. But a political stalemate
   developed as the party and others tried to draft the country’s new
   constitution. The Islamists failed to improve a slumping economy. And
   Ennahda came under fire for what many Tunisians saw as a failure to crack
   down on Islamist extremists.

   Map: Flow of foreign fighters to Syria

   After the collapse of the authoritarian system in 2011, hard-line Muslims
   known as Salafists attacked bars and art galleries. Then, in 2012,
   hundreds of Islamists assaulted the U.S. Embassy in Tunis, shattering
   windows and hurling gasoline bombs, after the release of a crude online
   video about the prophet Muhammad.  The government outlawed the group
   behind the attack — Ansar al-Sharia, an al-Qaeda-linked organization — and
   began a crackdown. But the killing of two leftist politicians in 2013
   prompted a fresh political crisis, and Ennahda stepped down, replaced by a
   technocratic government.

   Tunisia’s current coalition government includes an Ennahda minister in the
   cabinet. Still, many leftist figures openly oppose collaboration with the
   movement’s leaders.

   “Ennahda is responsible for the current deterioration of the situation,
   because they were careless with the extremists” while they were in power,
   Azzouz said.

   The leader of Ennahda, Rachid Ghannouchi, condemned Wednesday’s attack,
   saying in a statement that it “will not break our people’s will and will
   not undermine our revolution and our democracy.”

   Security officials are particularly concerned by the collapse of Libya,
   where various armed groups are vying for influence and jihadist militants
   have entrenched themselves in major cities. Tunisians worry that
   extremists can easily get arms and training in the neighboring country.

   In January, Libyan militants loyal to the Islamic State beheaded 21
   Christians — 20 of them Egyptian Copts — along the country’s coast. They
   later seized the Libyan city of Sirte.

   Officials are worried about the number of Tunisian militants who may have
   joined the jihadists in Libya — with the goal of returning home to fight
   the Tunis government.

   Ajmi Lourimi, a member of Ennahda’s general secretariat, said he believed
   the attack would unite Tunisians in the face of terrorism.

   “There is a consensus here that this [attack] is alien to our culture, to
   our way of life. We want to unify against this danger,” Lourimi said. He
   said he did not expect a wider government campaign against Islamists.

   “We have nothing to fear,” he said of himself and fellow Ennahda members.
   “We believe the Interior Ministry should be trained and equipped to fight
   and counter this militancy.”

   The last major attack on a civilian target in Tunisia was in 2002, when
   al-Qaeda militants killed more than 20 people in a car bombing outside a
   synagogue in the city of Djerba.

   Heba Habib contributed to this report.

   Read more:

   Tunisia’s Islamists get a sobering lesson in governing

   Tunisia sends most foreign fighters to Islamic State in Syria

   Tunisia’s Bardo museum is home to amazing Roman treasures
