"The myth of 1639 and Kasri Sirin
Soner Cagaptay and Duden Yegenoglu
With Iran's nuclearization a hot button issue, analysts are asking how Turkey, the only NATO country bordering Iran, would respond if the US imposed sanctions on Tehran or chose a military option to prevent Iran from acquiring a nuclear weapon. There is one answer that American policymakers will hear in Ankara: Turkey should not confront Iran because Turkey and Iran have been good neighbors since the 1639 Treaty of Kasri Sirin (also called the Treaty of Zuhab). Turkish policymakers assert that the two countries have neither fought nor changed their mutual border since 1639. "
More:bitterlemons-international.org - Middle East Roundtable