The says fielded systems have limits against swarms of medium-sized attack drones of the kind seen in the US-Iran war. It argues the core problem is the cost of shooting them down, because cheap drones can force defenders to use far more expensive interceptors.
Citing a Center for Strategic and International Studies analysis, the report says US Patriot interceptor stocks fell about 65 percent by late July from February levels, and THAAD stocks an estimated 40 to 50 percent. It also says South Korea's protective and portable counter-drone systems rely largely on electronic jamming, which is less effective against autonomous drones that navigate without external signals, and that lasers could be a cheaper option.
These are the institute's assessments as reported by the Herald; the interceptor figures are the institute's citation of CSIS, not checked here.
Limits
Assessment as reported by a newspaper; the report itself was not read and the CSIS figures are second-hand.