Neutralising Iran could make crude oil much cheaper because the threat posed by Tehran imposed a "terror premium" that inflated global oil prices for decades, a top White House adviser said in a report to be released on Monday. Peter Navarro, who leads the White House Office of Trade and Manufacturing Policy, has written in a 13-page report that tensions with Iran have added a $5/bbl to $15/bbl premium to crude prices, as markets price the risk of attacks or disruptions through the critical oil transit route of the Strait of Hormuz. Reuters viewed a draft of the report prepared by the White House trade and manufacturing office.