Just a little more than a year ago, Iran and Saudi Arabia restored diplomatic relations in an agreement signed in China. The accord—which followed two years of talks hosted by Iraq and Oman—entails the reactivation of the 1998 and 2001 cooperation and security agreements reached between Riyadh and Tehran during a previous period of détente.

Both Iran and Saudi Arabia have taken steps to build on their diplomatic breakthrough. There has been a reopening of embassies with a return of ambassadors, and a fruitful bilateral dialogue has continued. That the Israeli war on Gaza’s ripple effects have not derailed the détente speaks to Riyadh and Tehran’s vested interests in managing tensions through diplomacy and a commitment to non-aggression. Neither side desires a return to the hostility that shaped bilateral affairs...