You've raised a point that you most likely don't understand yourself. The US needs an agreement for it's purpose of manufacturing a lie on Iran not abiding by the agreement.
But the other parties to the old agreement are solidly decided that Iran was honouring the agreement and Trump destroyed it for no good reason.
Beyond all the b.s. by the US, there's the fact that the US and the Zionist regime don't really want any kind of agreement. They both want an excuse to go to war against Iran.
So the question is, will they start a war, regardless of the repercussions and great danger of China and/or Russia reacting along with Iran?
America wants war with Russia and this could be where the spark is ignited. If not the Ukraine?
I think Biden understands the need for great caution and restraint from now on over America resorting to more wars.