Former Israeli defense minister and mentor of Israeli Prime Minister Benjamin Netanyahu, Moshe Arens, passed away on Monday at the age of 93.

Arens’s family managed to escape the Holocaust by moving from Lithuania to the United States in 1939. A leader in the Beitar youth movement of Ze’ev Jabotinsky, Arens served in the U.S. Army Corps of Engineers during World War II, but made aliyah in 1948 and joined the Irgun paramilitary organization, against the wishes of his parents.

A founding member of the right-wing Herut political party, along with Menachem Begin, Arens then returned to the United States, studying aeronautical engineering at MIT and Caltech, and marrying his wife Muriel.

The couple returned to Israel, and Arens taught at the Technion. In 1962, he was appointed deputy head of Israel Aircraft Industries, helping to develop Israeli Kfir fighter jet, and the Israeli Arava cargo plane, two projects which ultimately earned him the 1971 Israel Defense Prize.

Arens was elected to the Knesset as a member of the Likud Party in 1973, serving until 1992, and then again from 1999 to 2003.

Arens, critical of Israel’s peace treaty with Egypt, refused a defense ministership under Begin, instead become the Israeli Ambassador to the United States. He became Israel’s Defense Minister in 1983, replacing Ariel Sharon, and served in that position three times over the course of his political career.

Arens is considered to be one of Israel Prime Minister Benjamin Netanyahu’s most formative mentors, taking him to the Washington embassy in 1982 and appointing him deputy minister of the Foreign Ministry in 1988, the first high-level public-service positions the young Netanyahu held.

In a statement by Netanyahu, the prime minister called Arens “my teacher and master,” and praised him as someone who “did wonders to strengthen Israel as our ambassador in Washington, as foreign minister, chairman of the Foreign Affairs and Defense Committee, and as defense minister time and again. … There was no greater patriot than him. Misha, I loved you as a son loves a father.”

President Reuven Rivlin called Arens “one of the most important ministers of defense the State of Israel ever had. He was not a commander or a general, but a devoted man of learning who labored day and night for the safety of Israel and its citizens.”

Across the political aisle, former Labor Party leader Isaac Herzog called Arens “an example of a clean and sincere leader and public servant who always spoke his mind and contributed tremendously to Israel’s security and standing among the nations of the world.”

“Even when we disagreed, we respected each other,” he said.

Arens passed away at his home in Savyon, and leaves behind his wife, four children and nine grandchildren.