Capito has sponsored approximately 40 bills about international trade and international finance, the most of any other legislative topic during her career. Capito has criticized the vulnerabilities in current national security policy in the wake of the San Bernardino terrorist attack and has sponsored 8 bills on the military and national security. Capito was one of 47 Republican senators to sign Senator Tom Cotton's open letter to the Iranian government in 2015. The letter, which sought to dissuade Iran from reaching an agreement with President Barack Obama regarding nuclear peace, was described by the White House as "undercutting foreign policy".