Given modern technology, no country can launch a surprise attack involving a large army. Satellites in orbit will see everything. That is why the world press reported the Russian invasion at least a day or two before it happened. Similarly, something such as Japan’s attack on Pearl Harbor over 80 years would be impossible in 2023.
One thing a country can do is limit the attack in size, to basically a glorified commando raid, and to have bases close enough to the border that the other side won’t see the troop movements. This is what Hamas did in Gaza.