Mark Marengo and Vasudha Saxena are both helping lead JPMorgan's $1.5 trillion effort to boost national security.JPMorganTwo leaders on JPMorgan's $1.5 trillion security initiative share why the work is uniquely challenging.Transactions often involve more stakeholders and complex structures than traditional banking deals.In some instances, the lean team is looking for "unicorn talent."Vasudha Saxena is the woman running the "engine room" of what…