I mean, the term "attack" is being used kind of loosely here.

You could legitimately call the explosions that the GRU set off in Czechia back in 2014 an attack.

It wasn't an invasion, but it was members of the Russian military destroying a Czech military munitions depot.

Or the assassinations. Moscow wasn't off killing people on NATO soil during the Cold War the way they have been more recently.

and believe that Russian armed forces will need another five to eight years to restore the military strength they had before the invasion of Ukraine.

Honestly, that also depends on how you measure it.

I would imagine that they can rebuild the numbers in the military and build up expertise again in that period.

And they'll probably have newer and better weapons, and re-equip that military. In terms of, say, drones, I'd bet that they'll be a rather-more-capable military than they were going into the war. Probably longer-range artillery.

But I also do not think that Russia is going to rebuild the kind of huge stockpile of (older) arms from the Soviet era that they have used against Ukraine and lost. Not in five or eight years, at any rate.

https://www.newsweek.com/russia-artillery-mlrs-losses-ukraine-shells-1868072

Moscow's troops have lost nearly 10,000 artillery systems in the more than 23 months of war, according to figures published by Ukraine's military. Russia has lost a total of 9,411 artillery systems since February 2022, including 24 in the past day, Kyiv's armed forces said on Thursday.

That's a lot of equipment to lose.

The Soviet Union had pretty hefty military spending. It's hard to estimate it with much precision -- non-market economy, so price data is missing. But you can get a ballpark:

https://nintil.com/the-soviet-union-military-spending/

Given my chart, one would say that military spending was around 10-20% of Soviet GDP, so perhaps a compromise figure of 15%, around twice USA spending. However, Harrison 2003 leads some support to the idea that actual military spending was around 20%, at the upper range of the Cold War estimates. Being street bayesians, let's conclude that it was 18% for now.

And remember, that's peacetime spending.

For 2024:

https://www.lemonde.fr/en/international/article/2023/09/26/russia-plans-to-increase-its-military-budget-by-70-in-2024_6139811_4.html

Next year, the Russian defense budget will reach €107 billion, or 6% of gross domestic product.

This is a situation where Russia is engaged in an actual invasion and large-scale land war.

If Russia is spending 6% of GDP over two years into a war, I'm kind of skeptical that Russia is going to manage to spend 18% subsequent to the war. And even that level had to be maintained for a long time to accumulate that much hardware. And Russia was only about half of the population in the Soviet Union.