U.S. Defense Secretary James Mattis began a pre-holiday tour of military bases at the American Navy facility in Guantánamo Bay, Cuba, offering holiday cheer to the troops tasked with operating the jihadi prison on the island and urging them to be ready for war.

“I need you to be at the top of your game,” he told several hundred troops at the U.S. Navy base in Cuba, “citing their roles both as a fighting force and as a positive example for a divided civilian society,” reports Associated Press (AP).

The Pentagon chief did not visit the Guantánamo military prison itself, commonly known as Gitmo, but he emphasized the importance of keeping the Navy base running.

He noted that, regardless of the future of the prison, the Pentagon will not abandon the base.

“We need this base badly” as a strategic spot to conduct humanitarian relief and other naval operations, noted the secretary.

His trip comes days after U.S. President Donald Trump’s administration indicated that it may start making decisions on whether to release detainees still held at Gitmo (41) “on a case-by-case basis.”

The Trump government “is still considering whether or not to transfer detainees,” Air Force Maj. Ben Sakrisson, a Pentagon spokesman, told AP this month.

Currently, Gitmo still holds 41 detainees, including 26 who have been deemed “forever prisoners,” or too dangerous to release, but may ultimately be cleared for release. Former U.S. President Barack Obama’s parole-style board approved five of the detainees for transfer and military commissions have charged the remaining ten.

Later on Thursday, Mattis visited troops at Naval Station Mayport near Jacksonville, Florida, telling them to anticipate war.

“You must be ready,” he reportedly told the sailors, “and you must demonstrate you’re ready” in order to improve the chances of a peaceful resolution.

On Friday, the defense secretary is planning to visit Marines at Camp Lejeune, North Carolina, and soldiers at Fort Bragg, North Carolina.

North Korea reportedly came up repeatedly during conversations between Mattis and troops on Thursday.

While stressing that the goal against North Korea is to focus on finding a diplomatic solution with the help of China, Russia, and others, Mattis talked about what may happen if diplomats fail.

“If we have to do it [militarily], we expect to make it the worst day in North Korea’s life,” he said, adding that if war comes, “every submarine he’s got is to be sunk and every ship he’s got is to be sunk,” he said, referring to ruthless North Korean dictator Kim Jong-un.

Kim has repeatedly threatened the United States.

Nevertheless, Mattis described North Korea as a “not yet imminent but a direct threat to the United States.”

Although the secretary did not give any indication the Guantánamo facility would be used to house newly captured jihadists during his visit, he defended the way American troops have treated detainees there in the past.

“I am confident that we’re doing the right thing here,” declared Mattis.

Some human rights groups have accused U.S. troops at Gitmo of torturing prisoners.

Trump, who vowed to “load up” Gitmo with newly captured “bad dudes” as a presidential candidate, is expected to spend hundreds of millions on new construction at the U.S. Navy base that houses the Guantánamo detention center.

According to the latest assessment by the Office of the Director of National Intelligence (ODNI), nearly 30 percent of the detainees who had been released (728) as of mid-July 2017 are suspected (90) or confirmed (122) of having returned to terrorist activities.

Most (137) of the prisoners who are suspected or confirmed of having re-engaged in terrorism remained at large as of mid-July. The remaining ones are either dead (37) or in foreign custody (38).

U.S. officials believe some former Gitmo prisoners have been linked to the deaths of Americans after they were released.