Some 23 Thai ambassadors and consuls-general from 21 nations reported to Bangkok Wednesday, summoned by a ruling junta that wants to enlist them in forcing outspoken critics of the May 22 coup d’état living abroad to return home.

Since seizing power, Thailand’s military has quashed all forms of dissent. TV channels and radio stations were taken off air — although many heavily censored versions have now returned — several hundred academics and activists were detained, and stringent censorship is imposed on print publications.

The resultant hush has been stunning, with only those based overseas still willing to make strong criticism of the military regime. But now the heat is being turned on this vocal émigré group.

Jakrapob Penkair, a founding member of the grassroots Red Shirt movement and former government minister, tells TIME from exile that his 77-year-old mother in Thailand has been phoned up and threatened, while his younger sister has been bullied at work.

“It’s almost natural [to be threatened] in Thailand now, unfortunately,” he says. “But I don’t see this as a big problem as I could never have gone this far without my family’s consent.”

Thailand’s 12th military coup since the end of absolute monarchical rule in 1932 was staged ostensibly to maintain order after six months of street protests that claimed more than 28 lives and threatened to escalate further. Thai Army chief General Prayuth Chan-ocha says that reforms will be carried out for over a year before elections — and he demands total support.

“Political groups and parties and leaders of the different sides of the political divide need to be careful when they say they don’t trust or have confidence in the [junta’s] work,” Prayuth told reporters Monday, reports the Bangkok Post.

And so, while the official reason for Wednesday’s powwow is to urge Thai diplomats to assure their host countries that elections will eventually be held, “there is a hidden agenda to put pressure on critics of the coup, especially to seek cooperation from the host country to send us back home,” says Pavin Chachavalpongpun, associate professor of Southeast Asian Studies at Japan’s Kyoto University, and one of the dissidents wanted by the regime.

“My family has not yet been threatened but I have already told them to be prepared,” he says. “I am anticipating this as other people have told me that when they ran away [military officials] came to their houses to annoy and humiliate [their families].”

Other than intimidation, diplomatic pressure may be employed. Pavin has been assured of support from his university, and does not believe Japan would kowtow to any repatriation request, but fears the next step may be to revoke his Thai passport, forcing him to seek asylum.

“Before [revoking my passport] they would have to issue an arrest warrant, but I have not done anything wrong — just my job as an academic,” he says. Even so, “I know an arrest warrant may still arrive.”

Jakrapob reveals that plans to set up a government in exile have been shelved, but an organization of “peaceful resistance” will be announced in coming days. “Points of mission will be set out so that people know what we are doing to resist the dictatorship in Thailand, which has become more and more vicious by the minute,” he says.

Write to Charlie Campbell at charlie.campbell@time.com.