Hard to believe, but before he was inaugurated Biden was considered one of those adults in the room. From Michael Tracey at mtracey.substack.com:
There was a recurring theme during the presidency of Donald Trump that went something like this: Trump’s most impetuous and destructive instincts — particularly in the realm of foreign policy — were being nobly restrained by the so-called “Adults in the Room.” Thank heavens! These impressive “adults,” a cadre of seasoned military men serving in Trump’s administration, included James Mattis (Defense Secretary), H.R. McMaster (National Security Advisor), and John Kelly (Chief of Staff). Their presence in the halls of power was supposed to be taken as a profound relief: whether you feared Trump would conspire with Vladimir Putin to collapse “the rules-based international order” — likely because you heard that phrase intoned on some Think Tank webcast — or simply believed that Trump was nuts, you could rest assured that the fate of the Republic would be protected by this crew of Serious Adults watching gamely over Trump’s shoulder. If any crazy ideas got into his head, such as withdrawing US military personnel from overseas deployments or forging a diplomatic accord with Russia, they’d spring boldly into action and put a stop to it.