They are vehicles that can navigate terrain a wheeled vehicle cannot. So they could do anything from operate as pack "animals" for infiltration teams to be armed drones that creep along the ground, harder to detect than a flying one.
That seems like a rather limited view of the word "defense", more appropriate to football or hockey than warfare. Even for that you could have these drones patrolling the territory/shooting intruders.
But the word "defense" is much wider than that. Is the US supplying offensive weapons to Ukraine contributing to the national defense? Even if you feel the US should not be doing that, I hoe you can see the logic of people who do frame it that way.
And Ukraine's in a defensive war against an invader, and for that they have to go on the offense.
(Of course the US renaming the Department of War to Department of Defense in 1947 was 100% propaganda, or to be more charitable, aspirational. There is no question that it has been used offensively).
> Is the US supplying offensive weapons to Ukraine contributing to the national defense?
It's not. It's contributing to European security, and as such is necessary for the US to reaffirm their suzerainty over Europe, but it's not really about US defense and even less about National Security. (I'm glad they do btw, because we European powers would have left Ukraine fall after deciding it would be too expensive to help them…)
> European security is national security via geopolitics.
If you consider “national security” to be a meaningless buzzword and not an actual concept, you can say that. It's as accurate as saying “US sports results at the Olympics is a national security issue via soft power”.
Pretty much everything is “national security” by that standards.
> Being a global superpower has many benefits for US citizens.
Sure, but most of them don't have anything to do with national security.
> Drones and robots made attacks easier, did that help national security?
Large flying drones make patrolling a border easier. You don't have to worry about the pilot's fatigue level. Only fuel/battery.
The war in Ukraine clearly shows that smaller drones also help in attacking and defending. Attacking, by dropping bombs or spotting targets.
And defending, via spotting incoming enemy forces; spotting enemy artillery that is shooting at you, etc
> Drones and robots made attacks easier, did that help national security?
Yes because the enemy will have them eventually regardless of whether you develop them. Call it a Prisoner's Dilemma if you will, but it's the reality. Besides, unlike nuclear weapons, warfare with autonomous systems is not particularly more cruel than WW1 or WW2 style warfare.
There is little difference between offensive and defensive capabilities. It's all about destroying your opponent. This helps national security because it is an additional and advanced means of destruction that the enemy might not have.
