You are correct about Trump pushing for the pledge. But what I meant is that in a broader sense, both his presidency and Brexit showed that mutual commitments c

You are correct about Trump pushing for the pledge. But what I meant is that in a broader sense, both his presidency and Brexit showed that mutual commitments can change according to short-term political will. If the UK can leave the EU, then why can't it also leave NATO? It doesn't even need a referendum for that. Likewise, Trump or a similar figure might not follow what a treaty demands, or what their military commanders advise.