Yeah, the AI is dead-set on some crazy beeline where they get AT Crews very fast and go straight to Mechanized infantry, which may catch you off-guard on Deity. That's also why they generally get two eras ahead of you, even though if you check the Victory Conditions screen, they may have about the same number of techs as you and much less science per turn.
By that point in the game, though, you should have already neutralized your closes neighbour a looong time ago, so getting a surprise DoW isn't very likely. As long as you have some forces, you can repel their assaults even with much worse units, simply because the AI is just so terrible. Then you can get their whole economy on the peace deal to help you catch up.
You likely won't be able to get any cities from them at this stage in the game though, as their Information Era cities will have near (or over) 100 Strength, which is much more than your industrial/atomic eras units can ever dream of achieving. 
By that point in the game, though, you should have already neutralized your closes neighbour a looong time ago, so getting a surprise DoW isn't very likely. As long as you have some forces, you can repel their assaults even with much worse units, simply because the AI is just so terrible. Then you can get their whole economy on the peace deal to help you catch up.
You likely won't be able to get any cities from them at this stage in the game though, as their Information Era cities will have near (or over) 100 Strength, which is much more than your industrial/atomic eras units can ever dream of achieving. 
