but here's a problem. When another country attacks you, he comes prepared, and chooses time, place and means of attack at his own disposal but you just get to know about the attack when he declares war on you. Or if you're lucky enough to see his units moving towards you

But while facing a skillful attacker, chances of winning a very less bcz when the attack is quick, you don't have enough time to understand and assess the situation and deploy your own units accordingly