1. Israel blackmailed him on some issue (doubtful) or 2. This is really about the global reserve currency and the BRICS working to replace it, which would collapse our society when all the inflation our country has exported for decades would flood back.
Option 3 - iran has been threatening Western Society as well as the Middle Eastern contries for 47 years thru their proxies, terrorism, nuclear weapons and balistic missile programs. These countries kept their heads in the sand and President Trump realized enough is enough