China has no upside in helping the rest of the world while they try to keep from sinking. They are doing everything they can to make sure we share their pain.
Team Trump is using their tactics against them to make them pay a price by accelerating the economic decoupling from China and bringing more Off shored industry back home.
The Saudis and Russians are definitely interested in breaking the backs of American frackers with low oil prices, but they have to survive too and can only stand low oil prices for so long.
The Europeans have been stoking the media fear frenzy to sink President Trump so President Trump just took them at their words. If things are sooooo bad, better shut down travel to Europe for 30 days. If they actually are as bad as we are being led to believe, great. If they aren’t, even better.
The EU travel ban is going to really hurt the EU economy.
As to Russia and Saudi being able to endure the pain of low oil prices, it was reported earlier this week (I heard it on Fox Biz) that they have both built up war chests of about $500b each.
As to how long Russia and Saudi can endure the low prices, there's this (from the source linked above)...
Moscow said on Monday it could withstand oil prices of $25-$30 per barrel for 6-10 years. Riyadh, meanwhile, can afford oil at $30 a barrel, but would have to sell more crude to soften the hit to its revenue, according to sources familiar with the matter.It looks like these two oil suppliers have been preparing for this.
This is an act of war BTW.