You may have a somewhat distorted view of how intelligence, counter- intelligence and counter-espionage (NOT the same thing) agencies actually work. All intelligence work is highly compartmentalized, everything is on a need-to-know basis, so even having a highly placed mole (or several) in your opponent's organization is not necessarily catastrophic. You may get nothing of value about your enemy's long-term plans in Asia, or technical details of his latest submarine, for example, but your maps of his missile silos and your predictions of his next harvest may very well be right on target.

This is not to say penetration of espionage services has not caused serious damage to the other side, but rarely has it been decisive across the board.

It is only at the highest level, where this data is collated and integrated into national policy, is the possibility of a single mole potentially devastating. In fact, it is often complained that very good intelligence exists of enemy action which somehow never filters up to those in charge of integrating it all into a view of enemy capability and intentions which can guide policy.

Usually, when the dust settles, it is determined we really knew what the bad guys were up to all along, we just never connected the dots and put it all together in time. And of course, efforts to reorganize to counteract this tendency by increasing access to material to lower level operatives just make you more vulnerable to lower level moles. Finding the right balance is a difficult management problem.

And of course, the biggest problem is misinterpreting your enemy's intentions; for example, when your ideological propensities mislead you to mistake an enemy defensive weapons technology for a offensive one, and you wind up wasting resources defending against a threat that doesn't exist, neglecting those that do, and transmitting to the enemy the idea that you are the villain preparing for a sneak attack. It is amazing how actions can be misinterpreted, sometimes with tragic results, because one side thinks it knows what the other is thinking.