Is China being left behind in sparring between US-N Korea?

Donald Trump has been publicly prodding China for months to use its influence on Pyongyang but the US president last week directed his verbal salvos directly at North Korea, warning of “fire and fury” if it endangered the United States or its allies.
That prompted a defiant Pyongyang to threaten a missile attack on Guam, a tiny US territory in the Pacific that is home to major US air and naval facilities. 
The bellicose rhetoric overshadowed Beijing’s calls for restraint and political dialogue. “Beijing is not able to persuade Washington or Pyongyang to back down at this time,” the state-run Global Times tabloid conceded in an editorial on Friday. 
Here are three questions and answers on China's conundrum:

What is the best-case scenario?
China has consistently sought the resumption of the “six-party talks” (alongside Russia, Japan, South Korea, North Korea and the US), which collapsed in 2009 but could trumpet Beijing’s role as a mediator.
“Beijing could play the role of a chairman at these talks and boost its influence not only regarding North Korea but also South Korea and Japan,” said political analyst Willy Lam. 
“This would bolster its claim to semi-superpower status.”
But China’s proposal for peaceful dialogue appears to have fallen on deaf ears as the United States and North Korea ramp up the rhetoric.
“China has no real effective leverage to de-escalate the situation if both Trump and North Korea’s Kim (Jong-un) are reckless,” said Xu Guoqi, a foreign relations expert at the University of Hong Kong.
Does Beijing have sway?

Before his verbal attacks last week, Trump had been complaining that China was not doing enough to use its considerable economic leverage on North Korea.
On Monday, China’s foreign minister pledged to “implement ... 100 per cent” new and wide-sweeping UN Security Council sanctions that could cost the authoritarian regime $1 billion (Bt33.2 billion) in annual revenue.
But China, which accounts for 90 per cent of the North’s trade, has said it would not cut off humanitarian aid to the country’s poverty-stricken population. 
The US, Japan and South Korea would have to offer additional concessions to prompt China to consider using aid as a bargaining chip, analysts said.
“If Trump wants China to do more in terms of sanctions, Washington has to make significant concessions, for example in regards to the deployment of the THAAD missile defence system, trade issues or the South China Sea,” Lam said.
“In theory, China could cut off aid tomorrow.”
    
Would China fight for N Korea?
A cornerstone of Sino-North Korean ties is a mutual defence pact signed in 1961, eight years after the end of the Korean War. Still, analysts said it was a “mystery” whether either side would uphold the treaty should conflict really break out.
Beijing has long feared that a collapse of the North Korean regime would bring a flood of refugees across its border.
An editorial in the Global Times, a nationalistic tabloid, said on Friday that China’s actions should depend on who fires first. 
“China should also make clear that if North Korea launches missiles that threaten US soil first and the US retaliates, China will stay neutral,” the column said. 
“If the US and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so.”