Robert Kagan has solved for the equilibrium
Consider what it will mean if we decide that what Trump and Giuliani have already acknowledged doing in Ukraine becomes an acceptable practice for all future presidents. Sending the signal that other governments can curry favor with a U.S. president by helping to dig up dirt on his or her political opponents would open our political system and foreign policy to intervention and manipulation on a global scale. Every government in the world wishing to influence U.S. foreign policy will have an incentive to come to a sitting president with information on his or her potential political opponents.
That information might be related to investments or other financial dealings in a particular country, as in Ukraine. Or it might have to do with the behavior of a particular individual while traveling abroad — who he or she sees and what he or she does. Other governments will therefore have an incentive to conduct surveillance of political figures traveling through their countries on the off chance of gleaning some bit of information that could be traded in Washington for some favor. Nor would other governments be limited to what they can see in their own countries. They would have an incentive to dig into the lives of potential opposition politicians in the United States, through monitoring their social media and other Internet presences, their bank accounts and other personal information — as already happened in 2016, and which Trump openly welcomed then, too.
Here is the full piece. I mostly agree, but wonder if foreign governments haven’t already been doing this for some time, but hoarding the information rather than releasing it to select American politicians (no reason to encourage them further, of course).