[sokoloff]

The debris field would move generally with its original momentum, meaning I wouldn’t expect hitting one to take out the others in the same string.

[ascar]

If you're hitting it with a rocket the explosion should considerably change the momentum, no?

But not that it's really relevant anyway, these things are not close to each other at all in this context.

[shlurpy]

Hitting it with anything at those speeds causes and explosion. At low earth orbit (LEO) most vectors cause the debris to rapidly deorbit, but a few can cause a slightly raised orbit that could hit things behind it. The problem is, if such a chain reaction does start, it's not likely limited to a single orbital plane like starling, but to destroy every single LEO satellite and make LEO unusable for tens of not hundreds of years.