Ri said the North has taken “significant measures pre-emptively, with maximum patience.”
“What a Christmas gift will be, that is entirely up to the United States,” Ri said in a statement that urged U.S. action.
North Korea has repeatedly demanded sanctions relief ahead of a fully verifiable denuclearization; the United States has refused to lift sanctions ahead of major changes.
Pyongyang has also called for the suspension of all U.S.-South Korea joint exercises, suggesting more missile tests could take place if drills are not suspended.
Ri’s warning to the United States came the same day North Korean state television showed footage of Kim Jong Un, wearing a black leather trench coat, attending a ceremony marking the completion of construction near Mount Paektu.
The footage did not include a message for the United States; KCTV stressed the power of “socialist Korea” advancing the “strength of self-determination, which cannot be stopped by any force.”
The North Korean leader’s entourage at Samjiyon, where the ceremony took place, included top North Korean officials Choe Ryong Hae, Pak Pong Ju and Hyon Song Wol, a musician and band leader who visited the South in 2018.
North Korea did not mention the latest flights of U.S. reconnaissance planes over the peninsula.
South Korea could also be stepping up surveillance of the North following more than a dozen round of weapons tests.
Hankook Ilbo reported Tuesday Seoul would begin to deploy the RQ-4 Global Hawk by the third week of December.
The Global Hawk is a high-altitude, remotely piloted aircraft that provides 24-hour surveillance and reconnaissance capabilities.