Assuming this was orchestrated by a nation state I wonder what the goal is? Just causing mayhem and incurring cost? Is there some specific function of these cables? Is this a negotiating tactic?
Likely this is just for "practice". This incident shows how easy it is to break the cables, and what methods the authorities in the area use to pin the blame. It also shows what effect breaking the cables did or didn't have. I doubt China cares about losing one ship. Next time the ship they send won't slow down while near the cable, which caught the eye of the authorities. Next time they will do a lot of things differently, but I have no doubt the next time is coming, just because they can.
If you have a plan to sever every major fibre link into and out of some country then the only way to rest the effectiveness of your plan is to sever just a couple and see what happens.
The Cold War equivalent is to fly up to the border and see how the enemy fighters intercept your bombers.
Alternately it’s “making a concrete statement” in response to a thinly veiled threat.
E.g.: if a western government threatens to cut Russia off from the Internet they can cut a fibre to two to make a point that the west is just as vulnerable.
The problem with seeing it as a test of response is that the test changes future responses. Where previously it might have been possible to do a surprise attack on cables, govts will now (hopefully) be looking at ships maneuvering near by with more suspicion.
