The National Samsung Electronics Union (NSEU) is planning a four-day strike in South Korea, starting on Thursday August 15, after talks relating to pay increases and staff bonuses broke down again.

Speaking during a live YouTube broadcast, Lee Hyun-kuk, vice president of the NSEU said the upcoming strike is “strategically designed to damage the company,” according to a report from Reuters.

On the live stream, Hyun-kuk said that the union now has more than 36,500 members, approximately 30 percent of Samsung Electronics’ South Korean workforce.

August 15 is a national holiday in South Korea, meaning many workers have already planned to take the day off, and Samsung could struggle to find enough backup workers to fill the labor shortages resulting from the strike action.

The NSEU has been staging strike action at Samsung Electronics facilities since June 7, when workers were asked to use paid annual leave in order to participate in an initial one-day walkout.

Union members are asking for an extra day of leave every year to mark the union’s founding, a 5.6 percent pay increase – as opposed to the 5.1 percent Samsung had signed off on, improvements to the company’s performance-based bonus system, and reasonable financial compensation to all union members who participated in the strike.

A second three-day walkout then took place on July 8 -11, but after Samsung’s management reportedly failed to engage with the NSEU, the union announced the strike would be extended indefinitely. However, after talks broke down in early August, the union asked members to return to work while it continued to try and negotiate with Samsung.

In a statement to Reuters, Samsung said: “The company plans to ensure there are no production disruptions and adheres to the no-work, no-pay principles, while we continue our effort to resume talks with the union."