For two core reasons:
#1 – “Trump’s position makes Iranian adventurism throughout the Middle East far less likely. It also decreases the temptation of U.S. allies to engage in counter-productive and destabilizing unilateral military operations of their own out of a perceived need to project strength in the face of Iran.”
#2 – “by restoring alliances with traditional allies in the Middle East, Trump’s approach is far more likely to get significant contributions from them, furthering his America First agenda.”
Here’s the Link to the article.