This only works during a “Cold War” one of the goals of intelligence is to prevent war by either maintaining your balance or superiority over your enemies and once a war breaks out provide intelligence that would grant you an advantage on the battle field.
However if a full scale war ever breaks down it will definitely regress back to leveling whole cities fairly quickly because in the end of the day it’s the only way to beat an enemy.
If the enemy could not sustain low levels of attrition even if key individuals they likely wouldn’t engage in a war in the first place.
However people over estimate how much intelligence should be credited to stopping all out war vs the economics of the connected world even during the Cold War.
Trade stops wars, hence why all recent wars have been civil in nature or ones against isolated actors of little to no economic importance on a global scale.
While a war with China might break out under extreme circumstances it’s highly unlikely when the US public relies on it for anything from their tooth brushes to their iPhones.
War with Russia is also extremely unlikely since half of Europe would freeze to death, they don’t need to nuke Berlin, as shutting off the gas supply would be nearly as devastating.
Russia’s reliance on natural gas to fuel not only their economy but also their geopolitical capita is also why it reacts so aggressively against European incursion eastward that could threaten their monopoly on LPG.
What Russia fears more than 500,000 NATO troops on its border is a Royal Dutch Shell pipeline going form the Caspian Sea through the Black Sea into Europe.
So while space death rays might seem to be effective they aren’t really not are they necessary today to actually prevent conflict between the big players.
With all the death rays in the world unless you’ll be willing to kill off the entire population of your enemies as long as they have enough peasants and rifles they can wage an effective war.
For China to effectively conquer a country they only need enough guns as nukes aside even the US might not have enough conventional weapons to deal with China if they’ll go bat shit crazy and issue a gun, an inflatable raft and a parka to every able man and woman of military age and tell them to march north west till the reach Alaska then start marching south.