Barcelona attack underscores Spain's vulnerability to terrorism

Spain has been the target of numerous terror attacks in the last few years. Here is a list of five of the more deadly events.

July 30, 2009 – Basque separatist group ETA exploded a bomb outside a Civil Guard barracks in Majorca, killing two officers.

May 14, 2008 -- ETA set off a car bomb near Civil Guard barracks, killing one person and injuring four.

Dec. 30, 2006 – A van bombing tied to ETA exploded in a parking area of the Madrid-Barajas Airport, killing two people and injuring 52. The airport sustained heavy damage.

March 11, 2004 – Muslim terrorists attacked Madrid's commuter rail system, killing nearly 200 people and injuring about 2,000. Officials said some 10 backpacks filled with explosives and shrapnel went off inside trains at four locations during the morning rush hour. In 2007, a court convicted 21 people, most of whom were Moroccan, on weapons possession and mass murder charges. They were linked to a cell acting to wage Islamic jihad.

April 12, 1985 -- Members of the Islamic Jihad organization exploded a bomb at the El Descanso restaurant in Madrid. The explosion killed 18 people and injured 82 others, including 11 U.S. servicemen, who were believed to be the target of the attack.

Spain’s history of and vulnerability to terror has drawn the attention of the U.S. State Department.

"Spain’s open borders with its western European neighbors allow possible terrorist groups to enter and exit the country with anonymity,” the department’s website says. “Like other foreign governments, Spain has taken actions to guard against terrorist attacks, including arrests of suspected extremists allegedly involved in terrorist plots. Credible information indicates terrorist groups continue plotting possible attacks in Europe."