Department of Homeland Security Secretary Kirstjen Nielsen called the Saturday panic an "unfortunate incident" during her appearance on "Fox News Sunday," indicating the problem must be handled by Hawaii state officials. And Federal Communications Commission Chairman Ajit Pai reported that a full investigation was "well underway," adding that "it appears the government of Hawaii did not have reasonable safeguards or process controls in place to prevent the transmission of a false alert."
President Trump, off for a golf weekend at Mar-a-Lago, told reporters that he was pleased that Hawaii officials "took responsibility." Although he said the federal government would now "get involved," he did not say how.
"That was a state thing, but we are going to now get involved with them. I love that they took responsibility. They took total responsibility. But we are going to get involved. Their attitude and their — I think it is terrific. They took responsibility. They made a mistake."
Tensions have been high in Hawaii over the president's charged exchanges with Kim Jong Un, the leader of North Korea, as it builds and tests its nuclear capabilities.
A North Korean missile launch would pose dire threats to Hawaii and take about 30 minutes to reach the islands, experts have predicted.
Regarding the North Korea threat, Trump said: "Well, we'll see what happens. They have got a couple of meetings scheduled, couple of additional meetings scheduled, we're going to see what happens. Hopefully, it's all going to work out."
Hawaii Emergency Management System officials said the incident was caused by human error — an employee pressing the wrong button during a training exercise.
Hawaii officials said the problem occurred about 8:05 a.m. Saturday when a worker faced two options from a drop-down computer menu: "Test missile alert" and "Missile alert."
"In this case, the operator selected the wrong menu option," agency spokesman Richard Rapoza said.
The result was a terse warning of a "missile threat" sent to mobile phones, televisions and radios across Hawaii. Reports from the scene suggested that many residents panicked, scrambling to seek shelter.
A White House official said Trump was quickly briefed by deputy national security adviser Ricky L. Waddell, who accompanied Trump from Washington to the president's Palm Beach club. He later discussed the episode with national security adviser H.R. McMaster and White House Chief of Staff John F. Kelly, the official said.
The federal government tracks North Korean missile launches through several means, including satellite surveillance, and officials around Trump would have known that no missile was detected.
Trump issued no statements about the incident Saturday. The only public mention came from deputy White House press secretary Lindsay Walters, who was with Trump in Florida and made clear that the federal government was not involved.
"The president has been briefed on the state of Hawaii's emergency management exercise. This was purely a state exercise," Walters said.
While there is no protocol that applies directly to such a mistake, past presidents have often weighed in to reassure the public at times of stress or threat.
The situation in Hawaii was made worse by the 38-minute gap between the initial alert and a follow-up message stating that the missile warning was a mistake.
Wireless emergency alerts are dispatched during critical situations — to warn the public of dangerous weather, missing children and security threats — and are a partnership of the FCC, Federal Emergency Management Agency and the wireless industry. Responsibility for sending those messages typically falls to emergency management officials.
Part of what worsened the situation Saturday was that there was no system for correcting the error, Rapoza said. The state agency has standing permission through FEMA to use civil warning systems to send out the missile alert — but not to send out a subsequent false-alarm alert, he said.
The state agency posted a follow-up tweet at 8:20 a.m. saying there was "NO missile threat." But it was not until 8:45 a.m. that a cellphone alert was sent telling people to stand down.
"We had to double back and work with FEMA [to craft and approve the false-alarm alert], and that's what took time," Rapoza said.
The agency said it has also suspended all internal drills until the investigation is completed. It will issue a preliminary report and corrective actions next week. The employee in question has been temporarily reassigned, Rapoza said, but there are no plans to fire him.
Mistakes with the emergency alert system are not uncommon.
In May, a training exercise in New Jersey led to a dire "NUCLEAR POWER PLANT WARNING" being broadcast to two counties near the Hope Creek nuclear power plant in Salem County. State officials blamed "a coding error" for that mishap.
In August, Guam residents were shocked by an alert of a "civil danger warning" broadcast by radio stations late at night. Guam is the closest U.S. territory to North Korea, and the country has explicitly threatened to attack Guam with missiles.
But Guam Homeland Security said the alert was a mistake and blamed human error.
Brian Fung and Anne Gearan contributed to this report.