“I must confess that the issue remains in the background of my thoughts," the first American pontiff says in a new book.
The US president may be forced to wage a political battle at home while presiding over a new war in the Middle East.
The US and Israel have launched a large scale attack on Iran, which President Trump says is an opportunity for Iranians to "take back their country".
Apparent Iranian attacks have been reported in Dubai, Doha, Bahrain, Kuwait, and elsewhere in the region. Earlier, Donald Trump said "major combat operations" were under way in Iran.