In the height of the Cold War, political scientist Aaron Wildavsky devised the "Dual Presidents Theory," which basically says there are effectively two versions of the United States President: one who deals in domestic policy and the other in foreign policy. This theory states that the President can move more unilaterally abroad than at home and that US citizens tend to not have as much at stake in issues regarding foreign policy than they do in domestic policy, meaning the President doesn't have as many ramifications to worry about when making foreign policy decisions.
This theory was tested when President Donald Trump left the country amid a growing political scandal at home regarding former FBI Director James Comey and how he interacted with the President. While the trip was planned far in advance of when the existence of the memos surfaced, the timing proved convenient as those domestic issues were basically dropped from public focus as soon as Air Force One's wheels left the runway.
The trip can be separated into two major halves, the first being a religious unity tour where Trump swung through Saudi Arabia, Israel, and The Vatican to meet with each country's respective head of state. These meetings went relatively well, and the only negative stories that came out of the visits were basically just memes.
More interesting is Trump's conduct with the second half of his trip, which basically served as a series of group meetings with other leaders of Western nations. These long-time allies to the United States were treated considerably worse, with Trump pushing aside the prime minister of Montenegro to be at the front of a photo op, scorned NATO other members for not paying enough for mutual defense (though this mostly just displayed Trump's misunderstanding of how NATO's rules set out defense spending in that regard), and further alienated other leaders of G7 countries with his indecision regarding the Paris Climate Agreement. On June 1st, Trump announced that the United States would be 'leaving' that agreement, justified that it will bring back American jobs (Spoiler: it's not going to).
Trump ran on the slogan "Make America Great Again," but these misguided steps to make people that voted for him think that he's helping them are only digging the nation deeper into an isolationist hole. It's not difficult to be the best United States of America on Earth, we're the only damn one. But being a global superpower gives us certain responsibilities as a nation. Not to invade other countries and make them do what we want them to do, but to lead and help the rest of the world out. But we're leaving that responsibility behind and at an important time too, China continues to grow as a superpower and is interacting more and more in the global community where our President used to stand.
In short, "America First" is the quickest way to becoming last.
