SEOUL, South Korea — North Korean leader Kim Jong Un toured the country’s key weapons factories, including those producing artillery systems and launch vehicles for nuclear-capable ballistic missiles, and pledged to speed up efforts to advance his military’s arms and war readiness, state media said Sunday. Kim’s three-day inspections through Saturday came as the United States and South Korea prepared for their next round of combined military exercises planned for later this month to counter the growing North Korean threat. [time-brightcove not-tgx=”true”] Tensions on the Korean Peninsula are at their highest level in years as the pace of North Korea’s missile tests and the joint U.S.-South Korea military drills, which Kim portrays as invasion rehearsals, have both intensified in a tit-for-tat cycle. Some experts say Kim’s tour of the weapons factories could also be related to possible military cooperation with Moscow that may involve North Korean supplies of artillery and other ammunition as Russian President Vladimir Putin reaches out to other countries for support in the war in Ukraine.