Israel’s increasingly isolated Prime Minister Benjamin Netanyahu took center stage at the United Nations General Assembly on Thursday, defending his decision to attack Iran as an easy one.

Allegations of Israeli genocide in Gaza are “the biggest lie of the century,” Netanyahu told world leaders in a defiant speech.

Netanyahu’s appearance in the hall was met with a mix of cheers, boos and mass walkouts. Scores of delegates trooped out and a majority of seats sat empty as he spoke.“If there are any other moral cowards who have not yet left the hall, please do so now,” Netanyahu said.

His voice rising in emphasis, Netanyahu said attacking Iran “was one of the easiest decisions I’ve ever had to make” and denounced as “moral cowards” delegates who walked out of the hall.

Palestinian President Mahmoud Abbas, 90, was forced to address the U.N. in a prerecorded video after the United States again denied him a visa to attend the General Assembly.