The major finding [of neuoreconomist Paul Zak and Ahlam Fakhar] is that factors that raise overall levels of oxytocin and/or estrogens (which increase oxytocin uptake) affect country-level measures of trust. Most prominently, these include the consumption of healthy foods (especially vegetables and fruits), clean environments, and some social behaviors. These are independent of the economic and legal factors that support trust and therefore provide a new rationale for governments and NGOs seeking provide healthier environments in developing countries: raising trust stimulates economic growth. Lastly, the strongest factor by far associated with a country's level of trust is...self-reported happiness. While the causation is likely bidirectional, we now know that trusting people are happier.
I suppose dropping oxytocin bombs across the middle east would run afoul of chemical weapons treaties.