World oil demands have been forecast to grow by 60% by 2030. This increasing demand, coupled with decreasing reserves, means that access to future oil supplies will be of enhanced concern to western governments from both a military and a political perspective. The ongoing conflict in Iraq, with its consequent impact on oil price rises and volatility, may be testimony to this concern. This article assesses the efficiency of international oil markets to assimilate US announcement information during conflict and non-conflict periods over an extended period of time.