China called on Monday for all countries to make constructive efforts to ease tension after North Korea said the latest U.N. sanctions against it are an act of war and tantamount to a complete economic blockade. The latest U.N. sanctions against North Korea are an act of war and tantamount to a complete economic blockade against it, North Korea’s foreign ministry said on Sunday, threatening to punish those who supported the measure. Meanwhile, US Defense Secretary Jim Mattis has urged American soldiers to be ready for anything, saying that “storm clouds are gathering” over the Korean Peninsula.