Maybe the Russian ship was testing successful countermeasures for the countermeasures.
Looks like I'm not the only one that had thoughts along those lines:
Missile defense test fails off Kauai after appearance by Russian spy ship
https://www.staradvertiser.com/2021/05/29/breaking-news/missile-defense-test-fails-off-kauai-following-appearance-by-russian-spy-ship/
Maybe the Russian ship was testing successful countermeasures for the countermeasures.
In the Reagan, era, we would have let them know that they succeeded, after they failed.
Maybe our countermeasures for the coutermeasure countermeasures were insufficient.