WASHINGTON - The United States is among the least peaceful nations in the world, ranking 96th between Yemen and Iran, according to a new index released on Wednesday that evaluates 121 nations based on their peacefulness.

A US soldier stands guard inside a house during an operation to look for explosives and weapons in the Sunni neighbourhood of Al-Jamia in Baghdad May 27, 2007. [Reuters]

According to the Global Peace Index, created by The Economist Intelligence Unit, Norway is the most peaceful nation in the world and Iraq is the least, just after Russia, Israel and Sudan.

"The objective of the Global Peace Index was to go beyond a crude measure of wars by systemically exploring the texture of peace," said Global Peace Index President Clyde McConaghy.

He said the inaugural effort proves "peace can and has and will continue to be measured."

The index was compiled based on 24 indicators measuring peace inside and outside of a country. They included the number of wars a country was involved in the past five years, how many soldiers were killed overseas and how much money was made in arms sales.

Domestic indicators included the level of violent crimes, relations with neighboring countries and level of distrust in other citizens.

The results were then reviewed by a panel of international experts.

"We were trying to find out what positive qualities lead to peace," said Leo Abruzzese, the North American editorial director of the intelligence unit that is part of The Economist Group that publishes the well known magazine.

He said they found in general the most peaceful countries were the smallest, the most politically stable and democratic.

"Democracy didn't actually correlate with peace, but a well-functioning democracy did. Efficient, accountable government seems to be the leading determinant of peace. Beyond that, income helps."

Fifteen of the top 20 most peaceful nations are in Western Europe, and countries with higher income appeared to lead to higher levels of peace, he said.

The United States ranked 96th out of 121 nations, just worse than Yemen and just better than Iran, Honduras and South Africa.

Abruzzese said the United States' score was pulled down by the number of wars it is involved in, large numbers of soldiers killed on the battlefield and high defense spending.

He said the fact the United States has the world's largest prison population per share of overall population also pulled down the score.

"It also has relatively high levels of violent crime," he added.

McConaghy said the index would be revised each year and increase the number of countries included. Some countries like Afghanistan and North Korea were not included in the first index because reliable data for all 24 indicators was not available.