Tunisian security forces stand guard near the National Bardo Museum in Tunis on March 19, 2015, in the aftermath of an attack on foreign tourists. Tunisia's president promised to wage a "merciless war against terrorism" after gunmen killed at least 17 foreign tourists and two Tunisians in a daylight attack in the birthplace of the Arab Spring. AFP PHOTO / FETHI BELAID (Photo credit should read FETHI BELAID/AFP/Getty Images)