There's a school of thought which claims the US military invaded Iraq in 2003 partly due to Saddam Hussein selling oil priced in the euro rather than the US dollar. Expositionary info:
Iraq nets handsome profit by dumping dollar for euroSaturday 15 February 2003 20.55 ESTA bizarre political statement by Saddam Hussein has earned Iraq a windfall of hundreds of million of euros. In October 2000 Iraq insisted on dumping the US dollar - 'the currency of the enemy' - for the more multilateral euro.
The changeover was announced on almost exactly the same day that the euro reached its lowest ebb, buying just $0.82, and the G7 Finance Ministers were forced to bail out the currency. On Friday the euro had reached $1.08, up 30 per cent from that time.
Almost all of Iraq's oil exports under the United Nations oil-for-food programme have been paid in euros since 2001. Around 26 billion euros (£17.4bn) has been paid for 3.3 billion barrels of oil into an escrow account in New York.
The Iraqi account, held at BNP Paribas, has also been earning a higher rate of interest in euros than it would have in dollars.
https://www.theguardian.com/business/2003/feb/16/iraq.theeuro The above article was published in february. The US invasion of Iraq occurred a month later in march.
A nation having its currency adopted as a reserve currency can be a method of control as well as a system for maintaining economic stability. China and russia choosing to denominate their oil in their own respective currencies rather than the US dollar, could be interpreted as a move on their part to escape the US influencing their affairs. Similar to russia creating their own version of the SWIFT financial network to avoid relying on a monopolized system they have no control over. It could also be interpreted as growing concern as america's deficit tops $20 trillion the rational response could be to avoid the dollar as a form of damage control if a worst case scenario occurs.
The biggest story here could be the media blackout on the USA and EU having massive deficits which are more dangerous than terrorists, war or anything else the media commonly cites as looming threats.