Nato leaders agree not to mention World Cup to Donald Trump to avoid irritating him
(www.theguardian.com)
The US in it's current form is definitely a threat to Europe in many ways, but not a military one. Not even in the case of an armed conflict about Greenland. I could see the leadership ordering to, but I can't see the soldiers on the ground shoot at people they've been training and fighting with their entire career. There will be mass defection on the side of the US if they are ordered to shoot (by then former) nato-allies. Unlike Russian 'soldiers', the fear of torture/execution will not motivate them.