How hard is modern military equipment to learn to use?

Say that some U.S. ally came under attack (we could say Ukraine getting attacked by Russia, although I don’t want to get too bogged down in specifics - any other nation would do, too.) And the United States, for whatever bizarre reason, decided to donate all sorts of military gear such as Abrams tanks, Arleigh Burkes, Apache helos, AC-130 gunships, even stealth fighters (hey, let’s even go further and say B-2 bombers, too) - …but without teaching the Ukrainians how to use any of it. The Ukranians are only accustomed to the existing warplanes, tanks, warships, etc. that they already have, which share no commonality with the gifted American stuff.

How long would it take the Ukrainians (or any other ally - Kurds, Jordanians, etc.), to master the stuff and put it to effective use in a war - or is the amount of stuff to be cram-learned simply way too much to overcome?

The answer is, it sort of depends.
I can’t speak about any branch than US Army, and my experience is decades out of date, but, depending on several factors, training time, are manuals included with the equipment, experience of the service members using the equipment (at all levels, not just individual/squad/platoon/company level) things like that. US Army equipment is designed to be simpler and easier to use(in conjunction with proper training) under adverse conditions.

Give a Bradley or an Abrams to a crew with even a little bit of experience with armored vehicles and while no where near proficient, they could probably figure it out enough to be dangerous to someone with similar training, maybe even without killing someone by accident.

My car has a lot of menus and I am not entirely sure that I have explored all the option, even after a few years and an online manual. Of course, I was able to drive it, Once I had worked out how the handbrake release worked, but turning the lights on etc took a while.

Now, I imagine that modern military equipment comes with a lot more settings and options, many of which would have to be set before the thing would even move, let alone do anything useful.

I used to drive trucks, and worked for an agency, which often meant climbing into a strange cab in the early hours and trying to drive off. There are dozens of different gearboxes; different ways of starting; seat adjusters… and these are just commercial trucks.

I would imagine a lot of it would depend on what they’re already used to; if we’re talking existing armor/aircraft crewmen who have trained on other US or possibly even Western equipment, then it might not be particularly difficult to use.

I suspect however, that the Ukrainians are going to primarily have Soviet/Russian equipment and are going to be familiar with it, so it might be a bigger change to learn Western stuff. If nothing else, the alphabet is different on the US/Western gear versus the Russian stuff.

That’s why when the US has done stuff like this in the past, we have supplied them with stuff they’re more familiar with - usually Soviet-bloc stuff, rather than dumping a bunch of A-7s and M-48s on them.

From my personal experience, it depends. On the low end, a lot of infantry weapons are idiot-proofed. The Claymore mine literally has “This Side Towards Enemy” stamped on the side you’re supposed to face towards the enemy. The AT-4 anti-tank rocket has instructions printed on the side, including pictograms. On the other end of the scale, if even an experienced fighter pilot tried to fly an F-22 without any specific training on it, I suspect they’d crash on take-off more often than they managed to get it off the ground.

I am reluctant to say a much of anything very specific about this (old security training dies hard, ask me how often I change routes to and from work every week) but for very basic shoot move and communicate, you would be wrong (20+ years ago that is)

Remember, these are, or were anyway, designed to be used when you’re getting shaken out of your fart sack in the middle of the night with inadequate sleep and having to go from zero to ohmygodkilleverythingbeforeitkillsme!!! in an instant while someone down range IS trying to kill you.

For somethings, things can be and sometimes are complicated, by design, so that you don’t do the wrong thing and kill the wrong people(ideally anyway) but for the basic functions, the controls are simple, the buttons and switches are large, in tanks and other armored and tracked vehicles, Imma not touching the flying stuff, that stuffs hard

It’s going to depend on the complexity and robustness of the system in question. You mention B-2s, Apaches, AC-130, stealth fighters, and Arleigh Burke destroyers in your OP; those will take considerable training, across multiple disciplines, for weeks, if not months, to be used effectively in combat.

Bradleys and Abrams are pretty complex once you start delving into the gun mechanisms and targeting systems. Starting an Abrams and driving it around you can teach in an hour (less, even). Performing crew-level maintenance and repairs? Gonna be a few classes. Boresighting the main gun system so as to be able to hit something more than the broad side of a barn at 1,200m+? Gonna need some real technical help from experts, there.

Of more importance than mere operation of said equipment is going to be crew training and integration, learning the tactics and techniques of effective war fighting with that particular weapon system. That requires more than a bit of schooling.

While I was an active USAF F-16 pilot I sat in a MiG-23.

I could not have started it. If somebody else started it I might have survived getting it into the air, but not back onto the ground.

And that was a lower tech machine than I was used to, but similar tech to older jets I’d previously flown.

I could certainly have been taught to fly it safely enough and fight with it some in a couple weeks by a qualified MiG driver. But cold turkey? No way.

There are some systems, like rifles, which can be taught to ok level in a week. On the other hand, in the Canadian Navy, I think the weapons tech specialty takes more than 1 year of job training. Becoming a pilot typically takes a couple years. I guesstimate it takes longer than that in some fields like electronic warfare.

As important and time-consuming aspect is having all of those systems and people act together. You might have B-2 pilots and airtanker pilots trained but that doesn’t mean they’re yet able to do a refueling mission in the middle of the Pacific at night while remaining undetected.

In a division, every individual may be individually trained but are they trained to cooperate as a whole at every level? That’s why you have training that starts at the lowest level and goes up, culminating in large exercises. Better informed people than me can say how long that takes.