Thai officials are searching for those responsible for 11 small bomb attacks that killed four people and wounded dozens of others in several key tourist towns Thursday night and Friday morning.
Police have said they do not suspect international Islamic militant groups were behind the attacks, instead calling them "acts of sabotage" likely carried out by a local group with a political agenda. Some officials have blamed elements in Thailand's Muslim insurgency in the country's deep south, but no group has claimed responsibility.
The bombings took place on the 84th birthday of Thailand's Queen Sirikit, a national holiday, and one of the blasts occurred in the beach resort town Hua Hin, where the king and queen have a palace. Thailand's military junta, which has run the country since its 2014 coup, sees itself as protectors of the monarchy.
The junta has cracked down on student activists and opposition political groups who have publicly criticized military generals for intervening in the country's political process. Since taking power, the junta also has come under heavy criticism from international rights groups for banning public protests, detaining political activists for "re-education" sessions at military-run camps, and tightening controls over the news media.
Last week, the military government's draft of a new charter was approved by voters in a nationwide referendum. Critics had slammed the vote as unfair because the military prohibited public campaigning on the issue ahead of the polls.
Thailand's military government seized power in a bloodless coup in 2014, arguing that it needed to stabilize the country after weeks of anti-government protests against the government of Prime Minister Yingluck Shinawatra. Thai leaders have said they plan to return the country to democratic rule under a new constitution, but have declined to give a firm timetable for the transition.