I wonder what kinds of capabilities you could have in a $25,000 mass produced balloon. 100,000 of those would only cost $2.5 billion. It seems like that would be a pretty overwhelming problem to deal with if your job was to suddenly get rid of 100,000 balloons.

I've played that game. You need monkeys with darts.

Additionally

Measure Response: Determine what an adversary nation does in response to the violation (what resources are scrambled, where do they come from etc)

Messaging: All the permutations of two sets of government folks trying to send a message the pair mutually understand re: defense etc

Tie up resources: Low cost provocation may divert higher cost resources and tie them up for a longer period of time since its a dwelling threat

Acquire signal information: Use sensors and measurement systems outside of the threat to measure the locations and signatures of tracking systems deployed to assess and monitor the threat

Deploy lightweight physical payloads: dust something of interest over an area etc