IMO the biggest threat to our wellbeing was Russia
That is incorrect. Our biggest threat, and probable successor as Number One Superpower, is China. They've been around for a long, long time, and have a lot of staying power. They also have a kind of regard for strong community that we lack. While that can repress individuality, it can also be a great national strength.
Trump could not "solve" one of those puzzles made for five year olds. While he can sometimes employ successful tactics, he is not a strategic thinker. Instead, he's impulsive. And that means guaranteed mid- and longterm losses. So if he wanted Iran not to have nuclear weapons, he should have stuck with the agreement Obama, the UK, France, Germany, Russia, and China negotiated. It was called the JCPOA. But the reliably childish Trump wanted no part of it because he'd had nothing to do with it. So he withdrew us from it in 2017, without having any replacement.
It's the sort of drama with a bad ending we've come to expect of Trump. Far from being the "Great Negotiator", he's a disaster. LOOK at the gigantic mess he's made in just four months. It's appalling.