Israel has confirmed the targeted killing of at least 14 scientists involved in Iran’s nuclear program—an extraordinary blow to Tehran’s nuclear ambitions that experts say may significantly delay, but not eliminate, its progress.

In an interview with the Associated Press, Israeli Ambassador to France Joshua Zarka said the deaths make it ‘almost impossible’ for Iran to continue building nuclear weapons, especially following nearly two weeks of Israeli airstrikes and U.S. bunker-busting bombs.

Zarka said, ‘The fact that the whole group disappeared is basically throwing back the program by quite a number of years.’

However, nuclear experts argue that while the strikes deal a blow, Iran’s scientific infrastructure remains resilient.

Western governments stress that military action alone cannot dismantle Iran’s accumulated nuclear knowledge.

‘Strikes cannot destroy the knowledge Iran has acquired over several decades, nor any regime ambition to deploy that knowledge to build a nuclear weapon,’ said UK Foreign Secretary David Lammy during remarks to Parliament.

According to Zarka, the strikes eliminated 14 senior scientists—including physicists, chemists, and engineers—who were directly involved in weapon design and production.

Israel’s military said nine of the scientists were killed during the initial wave of airstrikes on June 13 and had ‘decades of accumulated experience’ in nuclear weapons development.