The Iran gambit has risks and, if a final deal isn’t achieved after six months, the possibility of war rises. World leaders say President Obama’s credibility to enforce the deadline has been badly damaged. The interim nuclear deal struck on Sunday morning avoids outright confrontation with Iran for six months, but foreign leaders and international experts warned that the gamble over reaching a final deal could substantially raise the risk of open conflict. Over 200 officials, lawmakers, and experts from more than 50 countries were meeting at the Halifax International Security Forum as news broke over the weekend, many...