These military moves by China and Russia make sense if war breaks out between a US-led coalition including South Korea, Japan, Canada, and Australia (for starters) and North Korean forces. The extra forces would likely be used to stanch the tide of North Koreans expected to stream out of North Korea. In the unfortunate circumstance that sees North Korea's first use of a nuclear weapon, a US retaliatory strike would ensure that the radiologically damaged would seek care in China and Russia, care that China and Russia can ill-afford to provide on a large scale.
During a protracted conventional conflict, it seems likely that enterprising organizations in China and Russia would attempt to funnel weapons and aid to the North Koreans to keep the US-led coalition occupied while they ponder their strategic and tactical options. With the US bogged down in Iraq, Syria and Afghanistan, there are many moves that the Chinese and Russians could make contrary to US interests.
The political and pundit classes in New York City and Washington, DC believe that the Trump Administration will just kick the Kim Jong-Un tin can down the road for another US president. The same elites told us all that Hillary Clinton would, with great certainty, win the 2016 presidential election. After 100 days of the Trump presidency, they still shake their heads in disbelief. Yet, they seemed to believe fully in President Trump's punitive April cruise missile strikes in Syria undertaken after a Bashar Al Assad use of a nerve agent on his own citizens.
But Trump's people say that the time for "strategic patience" with North Korea is over. Secretary of State Rex Tillerson, the Perry Como of the US State Department, declared as much during a recent visit to South Korea. Has America's new Ken and Barbie, Jared Kushner and Ivanka Trump, been advising President Trump on the matter?