Gunmen killed one soldier and wounded another on May 31 when they opened fire on security forces escorting a team of polio workers during a door-to-door inoculation campaign in a former Pakistani Taliban stronghold near the Afghan border, police said. No one immediately claimed responsibility for the attack in North Waziristan in Khyber Pakhtunkhwa Province. It came days after the government launched the latest polio eradication campaign, said Aslam Riaz, a police officer in the region. He said the polio workers escaped unharmed and the attackers fled the scene. Pakistan and Afghanistan are the only countries in the world where polio remains endemic.