Claims

A 'trembling hand equilibrium' is optimal in game theory for deterrence: you want the opponent to be slightly uncertain about whether you might press the button, but not so uncertain that you actually do it (not 'pure shis'), and Ferguson questions whether Trump provides the right level of trembling or too much trembling to be reliable

Tit-for-two-tats is the optimal strategy in repeated games: you can let someone cross you once, but if they cross you a second time, you respond with full force; this is superior to tit-for-tat because it allows for error or misunderstanding while still establishing strong deterrence.

The Nash equilibrium is a state where all players choose their optimal strategy given their beliefs about other players' strategies such that no individual player can improve their outcome by unilaterally changing their strategy, and equilibria are frequently suboptimal for all players collectively compared to coordinated alternatives