On Monday, the citizens of North Korea celebrated the 101st birthday of Kim Il-Sung, the first leader of the country and the grandfather of its current leader, Kim Jong-un. Today, North Korea has issued more threats, continuing the rhetoric that has been sparking tensions on the Korean peninsula for weeks.

According to a report from Reuters, the new threats are related to South Korean protests that took place during the North’s celebration. Portraits of North Korean leaders were reportedly burned during the protests, and North Korea is now demanding an apology from South Korea. According to the report, North Korea has threatened “sledge-hammer blows” if it does not receive such an apology.

North Korea has been releasing inflammatory statements for weeks, criticizing joint U.S/South Korean military exercises near the border between the Koreas. The rhetoric has included the statements that North Korea now considers itself in a state of war and that it has rejected the Korean Armistice Agreement that ended the Korean War in 1953. The country has also cut off all communication with South Korea, including hotlines meant to stave off war. The U.S. has responded by deploying a greater military presence to the region, including F-22 stealth fighter jets.

In other North Korea news, former NBA star Dennis Rodman has stated that he will be returning to North Korea in August to “hang and have some fun.”