The narrow and congested Mideast waterway has become a site of escalating U.S.-Iran tensions. Conflict in the wake of tanker attacks there could jolt global oil supplies.

Ramped-up diplomacy in 2018 has eased tensions on the Korean Peninsula and led to a one-year halt in missile testing. But Pyongyang has not yet taken credible steps toward denuclearization.

The United States has reactivated sanctions against Iran that could trigger the collapse of the multilateral Iran nuclear deal.