WASHINGTON (JTA) — Daniel Inouye, the longtime Hawaii senator described by pro-Israel groups as one of Israel’s best friends in the Senate, has died.

Inouye, 88, and a decorated World War II hero, died Monday of respiratory complications at Walter Reed National Military Medical Center.

"Senator Inouye deeply understood the importance of the U.S.-Israel relationship, and as chairman of the Appropriations Committee, worked tirelessly and effectively to ensure that America’s ally, Israel, had the necessary resources to defend her people," the American Israel Public Affairs Committee said in a statement. "He will be missed by all who appreciated his many decades of leadership in strengthening the ties between America and Israel."

Inouye enlisted in 1943 as soon as a ban on Japanese Americans serving in the Army was lifted. He lost his arm in Italy in 1945 but persisted in leading an assault on a ridge heavily manned by German troops, an act that won him the Medal of Honor "for conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty."

Recovering in a hospital, he heard from a fellow patient about his discovering bodies in ovens at a camp liberated by U.S. forces.

Recounting the memory as recently as October, to students in a high school in Jerusalem, Inouye said he asked his fellow patient what their crime could have been. He was told "they were Jews," and the answer changed his life, The Jerusalem Post reported.

Inouye’s first job was selling Israel Bonds in Hawaii, and he considered converting to Judaism, but pulled back, worried that his devoutly Christian mother would be upset.

Inouye, first elected to the U.S. Senate in 1962, rose to become the top Democrat on its Appropriations Committee. He enjoyed a convivial relationship with Sen. Ted Stevens of Alaska, for years his Republican counterpart.

Pro-Israel Republicans and Democrats mourned his passing on social media. The National Jewish Democratic Council called Inouye "a true mensch in every sense of the word."

Inouye was a lead sponsor of the legislation in the mid-1990s that recognized Jerusalem as Israel’s capital. His role as a lead appropriator helped guarantee U.S. defense assistance to Israel.

"Our people owe him an immense historic debt," Michael Oren, the Israeli ambassador to the U.S., said in a statement. "The Iron Dome system that recently intercepted hundreds of terrorist rockets aimed at our homes stands as enduring proof of his commitment to the defense of the Jewish State."