The geopolitical tension between Saudi Arabia and Iran is reflected in the oil market and has repercussions on China, which imports about 16% of its oil from Saudi Arabia. It remains to be seen how Saudi oil sales to China will be handled. Oil futures in yuan will be in direct competition with oil futures in US dollars when it is a question of oil destined for China.
US President Donald Trump has experience with bankruptcy and finding financing to make a recovery. This will stand him in good stead as the financial situation of the federal government worsens. As the US dollar is the major global reserve currency, it is imperative for the US to avoid defaulting.
US debt is now at 21.6 trillion with a foreseeable budget deficit of around 650 billion. Add to that a negative trade balance of 798 billion, of which 376 billion is with China alone (US Debt Clock). It would be counterproductive for the Chinese to bring about a rapid depreciation of the dollar as they would be damaging themselves.