New York, Feb 22 (IANS): Economic sanctions are not effective tools for achieving specific policy goals in foreign nations, suggests a new research that looked into the effects of imposition of economic sanctions against Iran.

"Some people think that the nuclear agreement the United States reached with Iran in 2015 means that economic sanctions worked," said lead study author Bruce McDonald, assistant professor at North Carolina State University in the US.

"But Iran's nuclear programme was not why the US imposed sanctions -- they were put in place decades ago to protest the toppling of the Shah's regime and the Ayatollah's rise to power,” McDonald said.

"In addition, the fact that we had to engage in tense negotiations on the nuclear deal signals that the sanctions themselves were not effective," McDonald said.

"And that's consistent with existing scholarship examining centuries of data on economic sanctions; they don't work," he noted.

The findings were published online in the journal Armed Forces & Society.

The researchers argued that rather than encouraging a nation to adopt the desired policy, sanctions instead stiffen the resolve of a nation and encourage it to prepare for possible invasion or other military action.

"When faced with sanctions, nations militarise -- meaning that they increase the output of their defence sector," McDonald said.

"They recruit and train more troops and produce or buy more weapons. All of this has the effect of stabilising a nation's economy, making it better able to weather the sanctions," he said.

Iran provided a good case study for the researchers because it has been under sanctions since 1979, and because Iran has made its economic data -- dating back to the 1950s - publicly available.

Looking at the economic data, one can see how Iran's economy shifted once sanctions were imposed.

"Iran's economy actually improved after the sanctions were imposed,” McDonald pointed out.

"In short, policy makers need to take into consideration that there is no evidence sanctions work and that there is significant evidence that sanctions encourage foreign powers to boost their military sectors," he noted.