Not original commenter, but the basic idea is this: the rise of the dollar with respect to the Euro is the normal reaction of a sudden shock in oil trade. Countries that export oil (e.g. the USA) see a rise in their currency, countries that import a fall. That’s a natural consequence of Euro-countries needing dollars to buy oil.

The talk about Treasuries is at cross purposes: from a low just under 4% before the war, 10 year notes are now above 4.25%. That is the interest rate the US government has to pay to investors for the specific period of ten years.

If the rise in the dollar were caused by “safe asset” mechanics, then people would want to buy US Treasuries. This would reduce their interest rates, since the government could get them sold at a lower rate. Instead, investors want more money for US debt, indicating they are not comfortable with the long-term prospects of this war. (or the US economy more in general).

The big problem right now is that US debt and deficit are historically very high. High deficit means the government has to borrow money to cover what’s missing. If interest rates rise, then the government has higher interest payments to pay. That increases the deficit, which means even more money needs to be borrowed. The more the government must borrow, the higher the interest rates investors demand. If America isn’t careful, this could all end up with something like the Eurozone crisis of the 2010s, only much worse.