Above all, with thousands of satellites in LEO like Starlink, the early warning capabilities are much higher and possibility of launch phase intercepts much higher.
It depends on the tech and how much money we can spend on it.
Kubrick had fun in Dr. Strangelove mocking Turgeson for saying, "no more than 10, err, 20 million dead Mr. President" if we struck first. But one thing that should never be forgotten is that enemies such as China would be wiling to take 10-20% population loss if the US could simply be annihilated.
The fact that we simply ceded our unparalleled economic and military position after 1991 through the most feckless bipartisan policies imaginable should anger every American.