Sen. Tom CottonThomas (Tom) Bryant CottonSenate confirms Haspel to head CIA Democrats urge colleagues to oppose prison reform bill Trump-backed prison reforms face major obstacles in Senate MORE (R-Ark.) on Sunday cast Hillary ClintonHillary Diane Rodham ClintonDem targeted by party establishment loses Texas primary Penn to Hewitt: Mueller probe born out of ‘hysteria’ Trump claims a 'spy' on his campaign tried to help 'Crooked Hillary' win MORE as "reckless," citing emails on the Democratic presidential nominee's private email server that included references to the Iranian nuclear scientist who was executed there for treason.

"I'm not going to comment on what he may or may not have done for the United States government, but in the emails that were on Hillary Clinton's private server, there were conversations among her senior advisers about this gentleman," Cotton said on CBS's "Face The Nation."

"That goes to show just how reckless and careless her decision was to put that kind of highly classified information on a private server and I think her judgment is not suited to keep this country safe."

Shahram Amiri, an Iranian scientist who reportedly gave information to the United States about Tehran's nuclear program, was executed in Iran. Amiri was hanged for treason after giving "vital information to the enemy," according to a spokesman for the Iranian judiciary.

Cotton said Sunday that national security will be the top issue of the presidential election.

Cotton was also asked whether GOP nominee Donald TrumpDonald John TrumpRed states find there’s no free pass on Medicaid changes from Trump Trump meets with Moon in crucial moment for Korea summit The Memo: Trump flirts with constitutional crisis MORE had the temperament to handle making the kinds of decisions a president needs to make.

"I'm confident if the American people elect Donald Trump and they elect a Republican [Congress], that America will be safer and stronger in the world," he said. "Our streets will be safer and our country will be more prosperous."