also, there has been a pre-blitzkrieg time, when it was considered honourable to formally declare war, before one attacks.
Actually, Imperial Japan wanted to do just that before the attack on Pearl Harbour, too, but fucked up due to blatant incompetence and a tight schedule. The official declaration of war was to be delivered half an hour before the attack (in time to formally save face, but too late to allow for any meaningful preparations), but it took the embassy staff much longer to decrypt than anticipated, so they ended up delivering it only after the attack had already started. US intelligence had by then already decrypted and read it for long enough (actually, US intelligence, by that time, could regularly decrypt Japanese embassy ciphers faster than the Japanese themselves) to technically be able to effect a warning, but due to incompetence on the US side, that warning also didn’t make it to the relevant people in time. (There were more warnings that went unheeded. For instance a Radar station picking up the air raid while still miles out, dismissed as a scheduled flight of US bombers into one of the air bases on Hawaii, and a patrol ship detecting and sinking a submarine trying to sneak into the harbour, dismissed as the relatively inexperienced ship commander imagining things) So it was just a whole lot of incompetence on all sides.
Actually, Imperial Japan wanted to do just that before the attack on Pearl Harbour, too, but fucked up due to blatant incompetence and a tight schedule. The official declaration of war was to be delivered half an hour before the attack (in time to formally save face, but too late to allow for any meaningful preparations), but it took the embassy staff much longer to decrypt than anticipated, so they ended up delivering it only after the attack had already started. US intelligence had by then already decrypted and read it for long enough (actually, US intelligence, by that time, could regularly decrypt Japanese embassy ciphers faster than the Japanese themselves) to technically be able to effect a warning, but due to incompetence on the US side, that warning also didn’t make it to the relevant people in time. (There were more warnings that went unheeded. For instance a Radar station picking up the air raid while still miles out, dismissed as a scheduled flight of US bombers into one of the air bases on Hawaii, and a patrol ship detecting and sinking a submarine trying to sneak into the harbour, dismissed as the relatively inexperienced ship commander imagining things) So it was just a whole lot of incompetence on all sides.