Defensive military alliances enhance peace, study shows

The study, "Defense Pacts: A Prescription for Peace?," was published recently in the journal Foreign Policy Analysis. It was co-authored by Rice University Associate Professor of Political Science Ashley Leeds and Jesse Johnson, a Rice graduate student in political science.

For their research, Leeds and Johnson did exhaustive analysis of defense agreements from 1816 to 2001 that covered the whole world.

"We were interested in analyzing policy prescriptions that leaders of countries can adopt that might make war -- and also militarized conflicts short of war -- less likely," Leeds said. "War is costly, most importantly in terms of lives lost, but also in terms of financial resources, destruction of productive capacity and infrastructure, and disruption of trade. As a result, research aimed at discovering policies that can prevent war is valuable.

"We found that when a country enters into a defense pact, it is less likely to be attacked," Leeds said. "In addition, entering into defense pacts does not seem to make countries more likely to attack other states."

Leeds believes that this research has current policy relevance for the United States and other countries. "A current policy debate, for instance, is whether Georgia should be accepted as a new member of the North Atlantic Treaty Organization (NATO). If Georgia joins NATO, the U.S. and other NATO countries will be committing to assist Georgia if Georgia is attacked by another state, for instance, Russia. Some analysts are concerned about the U.S. making such a commitment, and some believe that having a commitment of assistance from the U.S. could encourage Georgia to behave aggressively toward Russia, making war more likely. The study suggests that this is not the most common general pattern. In fact, a defensive commitment to Georgia should, according to the study, make war between Russia and Georgia less likely."

Currently the United States has many defensive alliances, including with most of the Western Hemisphere states, NATO countries, Japan, South Korea and Pakistan, among others. The study suggests that due to their alliance with the U.S., these states are less likely to be attacked by rivals, and U.S. allies are no more likely to behave aggressively than they would be without a U.S. alliance commitment.