N. Korea to Seoul: Apologize for Protests or We'll Attack Pyongyang warns of 'sledgehammer blows' By Matt Cantor, Newser User Posted Apr 16, 2013 7:33 AM CDT 45 comments Comments South Korean protesters burn effigies of North Korean leader Kim Jong Un and late leaders Kim Jong Il and Kim Il Sung in Seoul, Monday, April 15, 2013. (AP Photo/Kin Cheung) (Newser) – While North Korea celebrated its first leader's birthday yesterday, South Koreans were busily protesting the occasion—and Pyongyang has had about enough of that. The North has threatened "sledgehammer blows" against the South if it fails to apologize for the demonstrations. "Our retaliatory action will start without any notice from now," said officials, per the official KCNA news agency. Yesterday, the North didn't issue any threats; some saw it as a hopeful sign for the region, the Guardian notes. Small protests in Seoul included burning pictures of Kim Jong Un; counter-protests sought talks between the countries. The North hinted at that possibility in threats today: "If the puppet authorities truly want dialogue and negotiations, they should apologize for all anti-DPRK hostile acts." President Obama is set to meet with South Korean President Park Geun-hye next month in Washington; they'll discuss "countering the North Korean threat," the White House says. Meanwhile, a US military helicopter crashed near the border with North Korea today during military drills, causing minor injuries to some of those onboard, the Wall Street Journal reports.