Morris served in the 1982 Lebanon War as an army reservist, taking part in the Siege of Beirut in a mortar unit. In 1986, he did reserve duty in the West Bank. In 1988, when he was called up for reserve duty in Nablus, he refused to serve on ideological grounds, as he viewed Israeli withdrawal from the occupied territories as a necessity and did not want to take part in suppressing the First Intifada. He was sentenced to three weeks in military prison and was imprisoned for 19 days, with the remaining two deducted for good behavior. He was subsequently discharged from reserve service.