WASHINGTON — A U.S. government review panel has approved the release of five men who have been held for years without charge at Guantánamo Bay, Cuba, according to a flurry of decisions released by the Pentagon on Tuesday, but they are unlikely to be freed soon as the Biden administration works to find nations to take them.

The disclosure came on the 20th anniversary of the establishment of the wartime prison, and President Barack Obama’s last special envoy on the task, Lee Wolosky, used the occasion to urge the White House to shut down the operation.

“Our longest war has ended, yet Guantánamo endures,” Mr. Wolosky wrote in a guest column in Politico. “If these detainees had been white and not brown or Black, is there any realistic chance the United States — a country committed to the rule of law — would imprison them without charge for decades? I don’t think so.”

Those recommended for transfer included three Yemenis, Moath al-Alwi, Zuhail al-Sharabi and Omar al-Rammah, and a Kenyan, Mohammed Abdul Malik Bajabu. All are in their 40s. None of them were ever charged with war crimes and instead were held as “law of war” detainees, the U.S. term for prisoners of the war on terrorism.

The Defense Department also released an order approving the transfer, with security measures, of Guled Hassan Duran, 47, of Somalia. His lawyers had earlier disclosed that he had been approved, making him the first detainee who was brought to Guantánamo Bay from a C.I.A. black site to be recommended for release.

Mr. Alwi, whom the review board deemed a low-level trainee with no leadership role in Al Qaeda or the Taliban, may be the best known of the five prisoners because of replicas of sailing ships he fashioned from objects in his prison cellblock. The models were the focal point of a show in New York on Guantánamo art, and the subject of an opinion documentary that imagined how he made them.

Diplomats working through country bureaus at the State Department, not a centralized Guantánamo office like the one Mr. Wolosky ran, have been seeking to make the arrangements. The plans have typically included pledges from the host country to restrict the detainees’ travel, provide opportunities for resettlement and sometimes enroll them in a jihad rehabilitation program, all aimed at preventing them from turning to anti-American activities.

It is against U.S. law to send Guantánamo detainees to Yemen, in part because it does not have a functioning government that can provide the security guarantees. So other countries would have to agree to take them in. Oman and Saudi Arabia have been key sponsors, with successful resettlement.

Of the 18 men now cleared, half are from Yemen and one is from Somalia, another country on Congress’s no-transfer list, along with Libya and Syria. A citizen of Afghanistan has also obtained permission to leave with security arrangements, but his release would require negotiating with the Taliban, who now rule the country.

Mr. Wolosky’s comments about the continuation of the detention center echoed criticism from activists who this week staged 20th-anniversary protests, including a rally on Facebook rather than the plaza of the White House because of the rise of the Omicron variant of the coronavirus.

“The time has come to finish the yearslong process of restoring U.S. moral credibility by untangling the knots that we ourselves tied in Guantánamo,” he said.

Mr. Wolosky served in the Clinton, Obama and Biden administrations, most recently as a special counsel to President Biden on the resettlement of Afghan refugees. As the last Obama administration special envoy for the closure of Guantánamo, he attained the title of ambassador and had the reputation of being a tough negotiator who in some instances sought to send detainees to other nations for prosecution or preventive detention.

For example, he tried unsuccessfully in 2016 to get Israel to accept Mr. Bajabu for trial, on the basis that he was suspected of having a role in the November 2002 car bombing of the Israeli-owned Paradise Hotel that killed 13 people in Kenya, and a failed surface-to-air missile attack on an Israeli airliner.

Mr. Bajabu was arrested in Kenya in 2007 and turned over to U.S. authorities. They considered him a facilitator for Al Qaeda’s East Africa affiliate who was involved in the attacks.

But the review board concluded on Dec. 27 that his release, with security assurances from a receiving country, was justified because he was a low-level extremist trainee before his capture. It also noted “the dissipation of the network of extremist associates with which he was previously involved.”

His lawyer told the board in September that Mr. Bajabu has a wife and three children in Somalia who were willing to relocate to Kenya, where he has “a large and loving family,” if he is repatriated there.

The lawyer, Mark Maher of the London-based legal defense organization Reprieve, called him a peace-loving man who poses no threat to the United States and “can quote Mohandas Gandhi and Dr. Martin Luther King like teenagers quote Taylor Swift.”

The board has six members from the Departments of Defense, State, Justice and Homeland Security, as well as representatives from the Office of the Director of National Intelligence and the Joint Staff. However, the six cabinet members make the ultimate decision.

The last 39 detainees at the prison fall into three groups: nine who are held as law-of-war detainees, the 18 who are approved for transfer and a dozen who have been charged with war crimes, two of whom have been convicted.

Among those still awaiting trial are Khalid Shaikh Mohammed and the four other men accused of plotting the Sept. 11, 2001, attacks. Pretrial hearings in the death-penalty case were scheduled for this week but canceled because of the rise in coronavirus cases at the base, which has instituted mandatory quarantines for all travelers upon their arrival.