Members of the Hyundai Branch of the Korea Metal Workers Union, joined by their counterparts at Hyundai affiliate Kia, staged partial strikes against the automakers Friday, Aug. 22, to protest stalled contract talks.

Workers at both companies called 4-hour strikes on both the day and afternoon shifts.

The KMWU says on its website it had no choice but to call a strike as Hyundai negotiators would not budge on any of the union’s major proposals, including the key demand that the automaker include bonus payments in its calculating basic wages.

Negotiations began June 13 and union spokesmen publicly advised Hyundai several times their members would strike if progress was not made. Roughly 70% of 47,262 members voted Aug. 14 to authorize strike action.

Union officials tell Reuters contract talks are to resume next week, but more partial strikes are likely if the deadlock continues.

Bonuses, which can exceed $10,000 in some years, currently are excluded from the base pay calculation. The basic pay rate is used to determine overtime pay and severance pay. If the company agrees to the demand it will add substantially to its labor burden.

The Hyundai union is not likely to compromise as Hyundai rivals GM Korea and Ssangyong Motor already have signed agreements with their unions that include the new basic wage formulas KMWU leaders are demanding of all of Korea’s automakers.