BEIJING: China said Tuesday its new ambassador to North Korea has taken up his post, in a sign the North is reopening amid reports it has been suffering heavily from the COVID-19 pandemic and food shortages.Wang Yajun will help in the development of the traditional friendship between the “close neighbors sharing mountains and rivers,” Foreign Ministry spokesperson Mao Ning said at a daily briefing.China is North Korea’s main source of economic aid and political support, but interactions have been disrupted by travel restrictions imposed in an attempt to prevent the spread of COVID-19.The ambassador’s posting comes as North Korean state media reported that leader Kim Jong Un urged his nuclear scientists to increase production of weapons-grade material to make bombs to put on the country’s widening range of weapons.The report Tuesday followed a series of missile launches — seven this month alone — and rising threats to use the weapons against North Korea’s enemies.North Korea’s weapons tests and US-South Korea military exercises have intensified in recent months, increasing tensions in the region.China’s support for both North Korea and Russia is seen as an act of defiance against the US-led liberal world order, along with ensuring security along its borders. While China has agreed to United Nations sanctions against North Korea over its nuclear tests, it has repeatedly assured the Kim regime of support to prevent its collapse and the potential humanitarian, military and political consequences that might ensue.