SEOUL, South Korea (AP) — North Korean leader Kim Jong Un is calling for another arduous march to fight severe economic difficulties, for the first time comparing them to a 1990s famine that killed hundreds of thousands. North Korea monitoring groups haven’t detected any signs of mass starvation. The term arduous march is a euphemism that North Koreans use to describe the struggles the famine. Kim’s comments suggest how seriously he views the current difficulties, which foreign observers say are the biggest test of his nine-year rule. Chinese data show trade with North Korea shrank by about 80% last year following North Korea’s border closure as part of stringent pandemic measures. South Korea says there are signs the North is easing border controls with China, its main trading partner.