A new book from the Foundation for Defense of Democracies (FDD), titled "Axis of Aggressors: Countering the Cooperation of China, Russia, Iran and North Korea," argues that the four authoritarian states are functioning as a strategically aligned bloc despite having no formal mutual-defence treaty. The authors warn that this deepening cooperation could force the United States to confront multiple serious crises at once, stretching its military and diplomatic resources thin, a scenario described as a "simultaneity problem."

The report details how the four countries support one another through military assistance, sanctioned energy trade, technology transfers and cyber cooperation, effectively pooling resources to circumvent Western sanctions and bolster each other's strategic positions. The FDD frames this as a coordinated, if informal, alignment that US policymakers must address across multiple fronts simultaneously rather than treating each country as an isolated threat.