ສົນທະນາທົ່ວໄປ

BANGKOK—A gathering that Thai officials held Thursday to discuss online anticoup dissent didn't go as planned for the military—because there were no social-networking companies in attendance.

"There are no social-media operators are here at all," Maj. Gen. Pisit Paoin, adviser to the Ministry of Information and Communication Technology's permanent secretary, told media after the meeting, noting that he had personally phoned representatives from Facebook FB -1.11% and Google GOOGL -0.37% to invite them.

Several Thai Internet service providers were on hand, but representatives from the world's biggest social network and the world's most dominant search engine were nowhere to be found, he said. Google and Facebook spokeswomen declined to comment on any invitation or questions about the army's approach to Internet censorship.

The incident illustrates a challenge that the ruling junta, known as the National Council for Peace and Order, faces following the military's first putsch of the smartphone age: Cyber critics are elusive, and the platforms they use to assail the powerful armed forces operate beyond Thailand's shores.

Maj. Gen. Pisit noted that officials will travel to Singapore to discuss the issue with Google and Facebook next month, and would consider visiting the headquarters of Japan-based Line—Thailand's most popular smartphone messaging app—at a future date.

Users have taken to Line and other services to organize antimilitary demonstrations since the putsch, and Maj. Gen. Pisit said blocking some individual users' Line accounts was "in progress."A Line spokeswoman, however, said the company hasn't been contacted by Thai authorities and that none of its users have been blocked.

Army officials have reiterated since they came to power last week that they won't tolerate social-media postings that denigrate the army or the country's royal family, but have not explained how they plan to block individual users without affecting entire social networks like Facebook and Twitter, which are hugely popular in Southeast Asia's second-largest economy.

"I think they may know what has happened in places like Turkey, but don't know if they would like to follow in their footsteps," said outspoken Thai academic Pavin Chachavalpongpun, associate professor at the Center for Southeast Asian Studies at Kyoto University.

A man used his mobile phone while riding the Bangkok sky train on May 28. Getty Images

Turkish Prime Minister Recep Tayyip Erdogan has undertaken a concerted effort to block websites and collect Web browsing data on individuals, leading to concerns among policy makers and Internet companies that Turkey could be used as a template for leaders in other nations who want to control Internet use without as much force as China or Iran.

For some, a prelude to the Thai military's tactics came on Wednesday, when Facebook—used by a large proportion of Thailand's 67 million people —briefly became unavailable, prompting outraged users to speculate on Twitter that it had been disrupted by the military. The army denied severing links to the site, however, and blamed the outage on a technical glitch.

Mr. Pavin, is one of those flouting the military's rules: When he was summoned recently to report to the army, he responded by posting a photo of his pet Chihuahua on Facebook. The irreverent message: He'd send his mutt, named Mooyong, to meet with troops in his stead.

"The political battlefield is no longer confined to the streets of Bangkok. It's moved into cyberspace," said Mr. Pavin. "This is the power of social media."

The global technological landscape has evolved dramatically in the years since 2006, when the military launched its previous military intervention. When the army unseated then-prime minister Thaksin Shinawatra, who was accused of corruption and disloyalty to the country's royal family, Facebook was just over two years old, and the iPhone had yet to be released.

Today Facebook has more than one billion global users and Thailand's smartphone penetration rate has risen to 49%, according to data from research firm Nielsen.

 "The military strategy is for immediate control, and then they'll manage the fallout later," said Singaporean academic James Gomez, who studies politics and social media.

If the Thai junta blocks social-media activity, users will simply use workarounds.

"A key value of social media is the ability to mobilize," he said. "They're trying to diminish that capability. The political grievances will continue."

Nopparat Chaichalearmmongkol in Bangkok contributed to this article.

Write to Newley Purnell at newley.purnell @wsj.com