SEOUL, South Korea — North Korea test-fired a suspected long-range ballistic missile that is designed to strike the continental United States, its neighbors said Thursday, days before the U.S. presidential election.

The White House characterized the weapon as an intercontinental ballistic missile, or ICBM, which have ranges of at least 3,500 miles and are designed mainly to deliver nuclear weapons. This would be the first ICBM launch since December for North Korea, a reclusive nuclear-armed…