WASHINGTON — President Joe Biden awarded the nation's highest recognition for valor in combat, the Medal of Honor, to four Vietnam War soldiers on Tuesday, saying it was "finally" possible to "set the record straight" after decades in which their actions were not properly recognized.

The men served in the Army and previously had received lower-level decorations for their battlefield gallantry. But after years of deliberation, senior military officials decided to upgrade each of their awards, and Biden approved.

"It's just astounding when you hear what each of them have done," the president marveled during a White House ceremony. "They went far above and beyond the call of duty. It's a phrase always used, but it takes on life when you see these men."

The recipients include Spec. 5 Dwight Birdwell, who led an armored unit through a bloody ambush in 1968; Maj. John J. Duffy, a Special Forces officer who fought off an attack in 1972; Spec. 5 Dennis M. Fujii, who, having survived a helicopter crash, directed airstrikes on advancing forces while under fire in Laos in 1971; and Staff Sgt. Edward N. Kaneshiro, who cleared a trench of enemy fighters using grenades and a rifle in 1966 and died a few months later in another battle.

Biden said that the awards were possible in part because of a congressionally mandated review of actions of Native Americans, Asian Americans and Pacific Islanders during the Korean and Vietnam wars. A similar review of underrecognized valor cases during World War II resulted in 22 Medal of Honor commendations, including one for the late Sen. Daniel K. Inouye, D-Hawaii, Biden said.

Birdwell, Duffy and Fujii stood at attention as Biden draped the award around their necks in the East Room of the White House. Kaneshiro's award was accepted posthumously by his son, John.

"It has been a long journey to this day for those heroes and their families, and more than 50 years have passed — 50 years — since the jungles of Vietnam, where as young men these soldiers first proved their mettle," Biden said. "Time has not diminished their astonishing bravery, their selflessness in putting the lives of others ahead of their own, and the gratitude that we as a nation owe them."

Birdwell, of Oklahoma, had previously been recognized with the Silver Star, the military's third-highest award for valor in combat, for his actions. But years later, his former commanding officer, retired Gen. Glen Otis, and other veterans of the battle pressed for more, Biden recalled.

Birdwell took action as North Vietnamese forces launched the opening assault of what would come to be known as the Tet Offensive, marked by coordinated attacks across Vietnam on U.S. troops, South Vietnamese soldiers and their allies. Birdwell's unit was called on to repel an attack on a major military installation, Tan Son Nhut Air Base, and was ambushed on the way.

Biden recalled how Birdwell's unit took the brunt of attacks, and that Birdwell took charge after his tank commander was gravely wounded, laying down suppressive fire as North Vietnamese soldiers shot at him.

"He used the tank's cannon, he used the tank's machine gun, he used his personal rifle," Biden said. "He sustained fire, drove back the attackers, and created a place of relative safety for injured men behind the tank to take cover."

Birdwell was hit by shrapnel but kept fighting. Eventually, he was ordered to board a helicopter to evacuate, but he crawled out the opposite side of the aircraft and went back to fighting.

"That's what you call taking orders and causing trouble," Biden said. "God love you."

Birdwell went on to a career in law and to serve on the Cherokee Nation's supreme court, Biden said.

Duffy earned his award during the Battle of Fire Support Charlie, when he was the only American serving on a base with South Vietnamese soldiers. He had been wounded twice in previous battles but refused to be evacuated, Biden said.

Working with the call sign "Dusty Cyanide," Duffy coordinated airstrikes under fire for hours on April 14, 1972, as enemy forces threatened to overrun their base. At one point, Biden recalled, he called in a strike "extreme danger close" on his own position to drive back advancing forces.

Duffy stayed with wounded soldiers on the base until the following day, rallying them to move as they were pursued by Viet Cong fighters. Duffy was the last to board the helicopter and caught a Vietnamese ally who was falling out of the aircraft after being shot, Biden said.

Duffy retired from the Army in 1977 and was later nominated for a Pulitzer Prize for poetry — the "definition of a warrior poet," Biden said.

Fujii received the award for his actions on Feb. 18, 1971, during a rescue operation in Laos that spiraled out of control after his helicopter came under fire and crashed. A second helicopter landed a few minutes later and recovered several other soldiers, but Fujii waved it off, fearing that it was too dangerous to keep the aircraft on-site.

Biden recalled that Fujii stayed behind and treated wounded Vietnamese allies in the field. The following night, they came under a renewed attack, and Fujii braved enemy fire repeatedly to coordinate airstrikes for the next 17 hours.

"Today, Specialist 5 Fujii, we remember and we celebrate just how many people you helped," Biden said.

The fourth Medal of Honor recognized Kaneshiro, who was raised in Hawaii by parents who were Japanese immigrants, Biden said.

On Dec. 1, 1966, his infantry squad was ambushed by North Vietnamese troops who were concealed in a village and protected by fortified bunkers, underground tunnels and a large trench. Other U.S. soldiers were killed, and Kaneshiro assaulted the trench while carrying his M16 rifle and six grenades, Biden said.

"Laying flat in the ground, Staff Sergeant Kaneshiro hurled his first grenade," Biden said. "It sailed directly through the aperture of the bunker, taking out the machine-gunner in the first throw."

Kaneshiro moved along the trench for 35 meters, killing other enemy soldiers as he went and preventing what could have been "a disaster for the whole platoon," Biden recalled. He was killed in action on March 6, 1967, about three months later.

"I hope today you take some pride and comfort in knowing his valor is finally receiving the full recognition it has always deserved," Biden told the Kaneshiro family.