SEOUL (Reuters). Thousands of South Korean truckers went on strike Thursday for a third time, disrupting shipments at ports and depots. This poses new threats to a stretched global supply chain.

The strike was called by 30% of Cargo Truckers Solidarity, who were demanding pay raises due to an increase in fuel costs.

South Korean President Yoon Suk-yeol warned strikers against using violence on Thursday and stated that the government was trying to solve the problem through dialogue.

The strike was called “extremely selfish” by a South Korean industry group, claiming it would add pressure to the auto industry already hurt by global chip shortages.

Yonhap news agency reported Hyundai Motor Co experienced some production disruptions at Ulsan’s plant because truck drivers were refusing to deliver parts to Hyundai’s plants.

Hyundai Motor did not comment.