Does the US realise that it holds most of the aces?

"China benefits from nuclear disorders," wrote Prof WPS Sidhu. China actively, if surreptitiously, helps Pakistan and North Korea to make nuclear weapons. Although India also has nuclear weapons we have signed agreements separating our civilian from military nuclear programs and agreed to inspections by the International Atomic Energy Agency. Why does China support 2 rogue nations? "China's active and tacit support of the nuclear programmes of Pakistan and North Korea respectively might be considered a form of deterrence (as the US has done by ensuring that its nuclear arsenal also covers its allies)." North Korea recently tested a new "high-thrust engine" so that its missiles are capable of reaching the US. Japan has a security treaty with the US under which the US is committed to defending Japan against external aggression and an exactly similar treaty exists with South Korea. The US is therefore keen to reduce North Korea's strike capabilities so that it is not tempted to attack either of its 2 allies. China has a border with North Korea and is its chief trading partner so the US wants China to pressure Pyongyang to stop both its nuclear and missiles programs. Despite Donald Trump's tough talk the US is following the same policy as Barack Obama did, wrote Prof Brahma Chellaney. During Secretary of State. Rex Tillerson's visit to Beijing recently he "echoed several Chinese bromides about the US Chinese relationship including 'win-win' cooperation", which the Chinese understand as a double win for themselves. But the Chinese may not be as clever as these professors think? Unlike his father and grandfather, Kim Jong-Un has never visited Beijing to pay his respects and Xi Jinping has visited South Korea but not the North. Donald Trump has said that the US is ready to act alone to stop North Korean proliferation if China is unwilling, or unable, to help. The US has deployed THAAD missiles in South Korea which worries Beijing. "In his first interview as secretary of state, Tillerson raised the possibility of both Japan and South Korea eventually obtaining nuclear weapons, something President Trump too has alluded to in the past," wrote Prof Harsh V Pant. This must be a nightmare scenario for Beijing. Missiles can go off course. What if a North Korean missile hits the South or Japan and they, along with the US, retaliate by bombing North Korean missile and nuclear sites? Will China defend the North or allow the regime to collapse and the two Koreas to unite? China has quarreled with all its neighbors by illegally enforcing a fictitious 'nine-dash line' to claim the resources of the South China Sea as its own. These are small countries and will not actively join the fight but will not do anything to help China. Donald Trump holds 3 of the 4 aces when he meets Xi Jinping later this weeks. Hope he knows that.