Events at US-run detention facilities in Guantanamo Bay in Cuba and at Abu Ghraib, in Iraq had proved damaging, Prof Patman said on Thursday.
The lack of a settlement involving Palestinian issues in the Middle East had also given Osama bin Laden - linked to the international terrorist group al Qaeda - a source of discontent which he could exploit.
Prof Patman, who is an international relations specialist in the Otago politics department, outlined his concerns about the rise of al Qaeda-linked terrorism in a public lecture at the university on Thursday night, devoted to "Strategic Shortfall: the 'Somalia Syndrome' and the March to 9/11".
The exit of US forces from Somalia in the 1990s and the subsequent "Somalia Syndrome" in US foreign policy had emboldened al Qaeda and indirectly contributed to the "9/11" terrorist attacks, he said.
During a battle in the Somali capital, Mogadishu, in October 1993, two US Black Hawk helicopters were shot down and 18 US servicemen killed.
Prof Patman said that al Qaeda had earlier contributed to the training of some militia fighters involved in the battle and had been emboldened by the unwillingness of the US to sustain further military casualties in the Somali conflict, despite its huge economic and military power, he said.
The Battle of Mogadishu had also contributed to the "Somalia Syndrome", with the Clinton Administration reluctant to use military intervention involving ground forces in civil war conflicts not perceived to directly involve US national interests.
There had been no military intervention to counter the Rwandan genocide in 1994, and air power only was used against the Bosnian Serb army in Bosnia in 1995 and the Yugoslav army in Kosovo in 1999.
Prof Patman said that since the "9/11" terrorist attacks on the US on September 11, 2001 about a third of the al Qaeda leadership had been killed, but it was of concern that the organisation remained strong politically.
