A question has been lurking in the back of my mind since news stories began mentioning the nuclear codes with unsettling regularity, North Korea began detonating bombs with alarming frequency and President Donald Trump began threatening Kim Jong Un with total destruction.

How do the nuclear codes work?

In the event of a nuclear attack on the U.S., there is no button for the president to push.

Instead, a series of codes must be relayed before 42 pairs of land-based missile operators in as many different locations can turn their launch keys to unleash a nuclear response.

If the president were to fire all 420 of those land-based nuclear warheads, plus 1,000 missiles aboard 10 nuclear submarines, it would equal roughly 30,000 Hiroshima bombs.