My take is also a missile, but as an interceptor, not offensive purposes. North Korea has shown that they can deliver a payload to Japan if they want. If the NKs do decide to launch something at Japan, it's not going to be tipped with conventional explosives. It'll be a nuke. Hypersonic interceptor seems the more likely application is this tech to me.
I think that hypersonic interceptors would use a rocket motor and not a ramjet, but I'm not sure.
I think this is for offence because I understood the advantage of this engine (compared to a rocket engine) is that you don't carry oxygen so you can carry more fuel and get more range. I think range is much more useful for offence than defence.
I am possibly making myself look foolish now as I'm not an expert on either rockets or ramjets and I might have incorrectly dismissed defensive applications.
Historically, it was: https://en.wikipedia.org/wiki/Sprint_(missile)
Would be handy today.
That era of ballistic interceptors all relied on large nuclear warheads to have any effect.
The modern, hard problem is avoiding using a nuke, because detonating a nuclear warhead above your own country is Bad