It's a difficult question. On the one hand, his foreign policy and habit of giving up deals are neither constructive nor conducive to maintaining the allied network. On the other hand, he promised all these things long before he was elected - so at least he kept his promises. I wrote an essay https://homeworkneeded.com on Trump's foreign policy and there are many subtleties. The question that needs to be asked is how much of what is happening depends only on Trump - and how much a real shift in attitudes and opinions from a large part of the United States is represented by Trump. If this is true, then the situation in which the West is now does not necessarily disappear as soon as Trump ceases to be at his post.