The governor of Guam said the island has defenses in place to protect it following a threat by North Korea to launch a missile strike against the American military base on the western Pacific outpost.

“I’ve reached out to the White House this morning. An attack or threat on Guam is a threat or attack on the United States. They have said that America will be defended,” Gov. Eddie Baza Calvo said in a video statement Wednesday.

“Guam...