The U.S. is not going to attack Iran, at least not in any meaningful way, and Iran’s lobbing missiles at Israel will not expand the war. Iran’s response to Israel’s attacks in Lebanon against Hezbollah and the death of Hassan Nasrallah is all diplomatically choreographed theater designed to show Iran’s proxies (Hamas, Hezbollah, Houtis) that they (Iran) are standing by their allies in the fight against the evil devils from the West, without resulting in major military action against it by the U.S. or Israel.
More likely than not, the intelligence behind the U.S.’ very public warning to Israel of an impending missile attack came through quiet diplomatic channels between the U.S. and Iran, who undoubtedly gave the U.S. advance warning it would be lobbing some missiles at Israeli military bases and U.S. bases in Iraq, with the purpose of giving the Israelis and U.S. time to train their Iron Dome and Patriot Missile systems at the incoming rockets, evacuate those targets, and minimize loss of life.
Why would Iran do this? The Big Picture. With their economy in crisis due to Western sanctions and a new, reform-minded and moderate president, it appears Iran is once again interested in revisiting talks with the West about restrictions on its nuclear weapons development in exchange for sanctions relief.
In the end, nobody wants an all-out war, but face must be saved, so Iran warns us it will be sending a few hundred missiles to specific military targets, most of which will be intercepted. Those that make it through will probably not result in loss of U.S. or Israeli lives because of the advance warning, but will cause some modest damage to infrastructure, which the Iranians can cite to their proxies as evidence they are still backing them in their fight against Israel and the West. Meanwhile, none of this derails the path towards eventual nuclear containment both sides want, albeit for different reasons.
Intrigue, obfuscation, misdirection, betrayal. All elements of great theater, but in this case, nothing to get too worked up about.