If we take a step back and look at the killing of Qasem Soleimani, it had at least two aims. (1) to kill the general (2) Trump take responsibility for the killing, maybe for personal gains to divert attention form impeachment or get more popularity in the November election.

Nothing can be done about the first part, though the 2nd can be turned against Trump quite easily. How?

Iran can continue whatever it wants, but why not take Trump to the international court of justice. Does not matter what would be the result, at least it would damage Trump reputation and let the democratic do the rest.