On August 23, 1944, during the widespread search conducted by the British in Petah Tikva, he was arrested as a 'terror suspect', brought to the Latrun internment camp and then sent to Eritrea with the first group of 251 detainees.
In the camp he joined the Irgun, and in February 1945 he was released. In Eretz Israel he commenced his underground activity despite his obligation to report daily to the police.
He was arrested again after the explosion at the King David Hotel, but was released shortly afterwards and returned to underground activity.
On December 29, 1946 he was captured armed, together with Alkahi and Dresner, upon returning from an operation. They were tried before a military court and sentenced to death.
On April 16, 1947 Kashani was hanged in the Acre jail. He was 24 when he went to the gallows.