The point with hypersonic missiles is that they can manoeuvrer until the terminal part of their trajectory, this in contrast to ballistic missiles which are on

The point with hypersonic missiles is that they can manoeuvrer until the terminal part of their trajectory, this in contrast to ballistic missiles which are on a set course past the boost phase. This makes it harder to shield against hypersonic missiles which is useful both for first-strike - more of your missiles will hit their targets - as well as when executing a counterstrike.