Extracted for brevity... (Russian breach via SolarWinds, VMWare and Microsoft)

...breaches at the Treasury and the Department of Commerce immediately raised concerns...investigation proved these concerns to be well-founded.
...information stolen in the attack would increase the perpetrator's influence for years... future uses could include attacks on hard targets like the CIA and NSA, or using blackmail to recruit spies. The amount of data taken was ....if printed would form a stack far taller than the Washington Monument.
(CISA) advised that affected devices be rebuilt...

How to evaluate an attack of this magnitude, other than a full-throated act of cyber-war?

[en.wikipedia.org]

(2020 United States federal government data breach)