For those that are curious, this is possible because the US has monetary sovereignty in a fiat currency. This means that the federal government is able to allocate literally trillions of dollars more than the annual budget without harming the economy in any way, because a vast majority of US debt (and deficit) is to the US federal government.
It brings up arguments for MMT (Modern Monetary Theory) which is one of the scariest boogeymen Republican leadership has ever heard of.... So you know it's probably fire and a very good option for future US. It's been years but Unfucking The Republic did an episode I really liked on it that could probably use a revisit.
Every country I know about has a fiat currency, but the monetary sovereignty bit is also important. Governments within the EU don't have monetary sovereignty, and therefore are limited by taxation. The EU as a whole could do the same thing, because they are the body that controls the Euro.
If you talk about currencies that are backed in gold, then none. The last country to abolish the Gold standard was Switzerland at some point in the 1990s.
What are you confused about? This is basic Modern Monetary Theory. The US government just decides that funding genocide is more worthwhile than helping the citizens.