SEOUL, South Korea — Starbucks’ South Korean operation said Monday it will close all of its stores nationwide early on June 22 for mandatory history and social sensitivity training as it reels from backlash following a marketing campaign that was widely perceived as mocking victims of a brutal military crackdown on pro-democracy protesters in 1980.

Shinsegae Group, which owns a 67.5% stake in Starbucks Korea, said group executives and employees at Starbucks Korea’s headquarters will attend training led by history and sociology professors on Wednesday. All Starbucks stores nationwide will close at 3 p.m. next Monday so employees can watch a recording of the session, Shinsegae said in a statement.

The coffee chain triggered an uproar when it attempted to promote a series of stainless-steel tumblers it called “SS Tank” by declaring May 18 to be “Tank Day.” The date marks the anniversary of the 1980 pro-democracy uprising in the southern city of Gwangju. It was violently suppressed by Seoul’s military government at the time, which deployed troops, tanks and helicopters, leaving hundreds dead or injured.

The campaign further fueled outrage by using the slogan “Thwack it on the table!” which many read as a reference to a notorious 1987 police statement that attempted to cover up the torture death of student activist Park Jong-chol. Authorities had falsely said Park died after investigators “hit the desk with a thwack.”

With the promotion sparking immediate backlash, Shinsegae canceled it within hours and fired the chief executive of Starbucks Korea. Shinsegae Chairman Chung Yong-jin later issued a nationally televised apology as police opened an investigation following complaints from relatives of the victims of the Gwangju crackdown. Chung will undergo separate training with the chief executives of Shinsegae affiliates on June 24.

Shinsegae said the decision to close all Starbucks stores early for the first time since the chain’s 1999 launch in South Korea and require companywide training shows “how seriously it views the marketing controversy and its determination to prevent a recurrence.”

The crackdown in Gwangju came months after General Chun Doo-hwan seized power in a coup in late 1979. Government records show about 200 people died in Gwangju, but activists say the true death toll was much higher. Chun’s government also imprisoned tens of thousands, saying it was rooting out social evils.

Public anger over Chun’s dictatorship led to massive nationwide protests in 1987, forcing him to accept a constitutional revision introducing direct presidential elections, which is widely seen as the start of South Korea’s transition to democracy.