It is a near consensus among scholars who have devoted their lives to the study of international security that the main drivers of great power competition are trending upwards. An under-analyzed challenge is great powers’ propensity to meddle in each others’ domestic affairs. Possessing by far the greatest capacity to make and break global orders, great powers belong in a class by themselves. In an anarchic, self-help world they are the most truly sovereign political actors, and so we would expect the politics surrounding mutual violations of that sovereignty to be different for them than between great powers and weaker states. Scholars don’t have a lot to say about this subject in part because so much of the behavior concerned is shrouded in secrecy and in part because the recent wave of research on electoral intervention and foreign-imposed regime change is dominated by data on big-vs-small power intervention rather than the rarer phenomenon of domestic meddling between great power peers. Bearing those limitations in mind, research by political scientists and historians suggest a few tentative propositions.
First, there is less that is novel/unprecedented in US, Russian and Chinese complaints against each other’s violation of the non-intervention norm than is commonly supposed. Needless to say, the norm itself is a standard piece of diplomatic hypocrisy so routinely violated that it’s amazing that people whose salaries are not paid by a government refer to it with a straight face. (For example, Carnegie Mellon Researcher Dov Levin shows that between 1945-2001 Moscow and Washington intervened to influence elections 117 times.) To take the Cold War case, influence operations were common, ranging from efforts to undermine figures in the rival power thought to be inimical to the intervener’s interests, to basic harassment, undermining, or weakening measures. For example, in the Cold War the Soviets used the CPUSA as an arm of policy attempting to influence American domestic politics and undermine the US global standing, while the KGB’s “Service A” conducted various and sundry “active measures” for years, including attempts to thwart the elections of certain candidates (e.g., Nixon), undermine the US by supporting various strains in the civil rights movement; discredit individuals via false information operations (Hoover, ML King, Scoop Jackson, etc). These featured forgeries, fake letters, fake news stories, bribery, infiltration, material and logistical support for conspiracy theorists, even a bomb set off in Harlem. For its part, the US government collaborated with ex-Nazis to recruit and assist nationalist insurgents in the USSR’s western borderlands in the early Cold War, and conducted systematic information operations throughout the Cold War including ongoing support for nationalist oppositionists in Ukraine and the Baltic states as well as varieties of reform movements within the Soviet elite.
Second, intervention in peer great powers’ domestic affairs is often ineffective and can backfire by generating security dilemmas deriving from each side’s fear of political subversion orchestrated by the other. Again, we can’t rule out that spectacularly successful covert interventions occurred that remain secret, but the evidence available is not positive. In the Cold War case, historians find that all the operations mentioned above failed miserably. Moreover, they generated two counterproductive effects in the target country: genuine apprehension about subversion and instrumental use of those fears by governments (or hardliners within governments) to push for ruthless countermeasures and, overall, a tougher policy. The net effect may well have been to increase tensions, rivalry, and war risks.
Third, the strategic calculations on all sides are dauntingly complex and resistant to generalization but the chief desideratum is expediency not norms or law. That is, what kept great power meddling at relatively low levels was not any reticence about the requisite lying and breaking of putative norms but rather opportunity, incentives, and escalation risks. In a nutshell, if you think you can advance your interests by intervening in a rival great power’s domestic affairs and you can keep the risks low—either because you are strong enough vis-a-vis the rival to control escalation risks or you can keep the operation so covert as to frustrate the other side’s ability to retaliate—you will do it. For example, the US aid to the anti-Soviet insurgency in the early Cold War never reached greater proportions (despite the fact that it was a serious insurgency) in part because of escalation risks but more because the US quickly learned that Stalin’s USSR was such a formidable counterinsurgent. And once the USSR obtained nuclear weapons, escalation risk dominated the US decision to scale down the program.
It follows that limits are very unlikely to emerge via international law or explicit policies or formal agreements and are more likely to emerge endogenously from interactions over time and attempts to establish salient thresholds and red lines via signaling and deterrence.