South Korea says Pyongyang has ignored Seoul’s deadline for responding to a demand for talks on a shuttered inter-Korean factory park, The Associated Press reports.

Unification Ministry spokesman Kim Hyung-suk said Friday, April 26 that Seoul is considering countermeasures but refused to discuss what they might be.

Pyongyang barred South Korean managers and cargo from entering North Korea’s Kaesong factory complex this month and recalled 53,000 North Korean workers. Seoul promised unspecified “grave measures” if Pyongyang didn’t respond to its demand for talks by noon Friday (0300GMT).

Some analysts said Seoul may pull out the roughly 175 South Korean managers who remain at the complex.

The suspension came amid weeks of North Korean threats aimed at Washington and Seoul over joint military drills and UN sanctions meant to penalize Pyongyang over its February nuclear test.