A group of Navy SEALs emerged from the ink-black ocean on a winter night in early 2019 and crept to a rocky shore in North Korea. They were on a top secret mission so complex and consequential that everything had to go exactly right.

The objective was to plant an electronic device that would let the United States intercept the communications of North Korea’s reclusive leader, Kim Jong-un, amid high-level nuclear talks with President Trump.

The mission had the potential to provide the United States with a stream of valuable intelligence. But it meant putting American commandos on North Korean soil — a move that, if detected, not only could sink negotiations but also could lead to a hostage crisis or an escalating conflict with a nuclear-armed foe.

It was so risky that it required the president’s direct approval.

For the operation, the military chose SEAL Team 6’s Red Squadron — the same unit that killed Osama bin Laden. The SEALs rehearsed for months, aware that every move needed to be perfect. But when they reached what they thought was a deserted shore that night, wearing black wet suits and night-vision goggles, the mission swiftly unraveled.

A North Korean boat appeared out of the dark. Flashlights from the bow swept over the water. Fearing that they had been spotted, the SEALs opened fire. Within seconds, everyone on the North Korean boat was dead.

The SEALs retreated into the sea without planting the listening device.

The 2019 operation has never been publicly acknowledged, or even hinted at, by the United States or North Korea. The details remain classified and are being reported here for the first time. The Trump administration did not notify key members of Congress who oversee intelligence operations, before or after the mission. The lack of notification may have violated the law.