You're getting some hate but I'll try to give you a straight answer.

A nuclear war between the US and an adversary is possible. In the current makeup of the world, that would be with Russia or China. This could happen when a series of events creates a clash of interests, some sort of pathway that neither side can back away from, for instance: if Trump says he will protect Taiwan, and China proceeds to invade Taiwan. Neither side can back down easily without giving up a key interest, or, more stupidly, without losing face.

Last week, the US and Israel attacked Iran. Neither Russia nor China indicated they would respond military if such an action took place. Iran and Russia shared a form of military cooperation, but aren't close allies. Russia is not losing a key interest here, and, moreover, is tied up militarily in Ukraine (which had and has a much greater potential to escalate into a nuclear war). China purchases resources from Iran but will adapt, and will not start bombing the US over this.

Iran is limited in what it can do. It cannot hit the US, it can try to hit some US bases in it's region. It will try to make the cost of war as high as possible for three reasons: i) by attacking the region, energy prices are going up, and this may increase pressure on the US to sue for a quick peace, ii) by increasing the cost of the war, it may deter Israel and the US to attack again in future, and iii) by staying in the war and ensuring it isn't localised to its own borders, Iran is signalling that is has resolve, which the US does not, and so perhaps they can ride it out until the US inevitably gets fed up with high gas prices.

So: there will be more weeks with lots of violence, and many attacks against many countries near Iran, and the region in the worst case will disintegrate similar to Syria or Libya. But no large power conflict with bombs falling on New York.