The idea that increased military power can promote peace.
The idea posits that with more military power, it will deter countries from declaring war. It can also be associated with a global peacekeeping nation, when one country can use their military might to patrol the globe and promote peace.
Peace through strength was most famously used by Ronald Reagan in the 1980s, but it actually dates back to the first century AD. It was first said by Roman Emperor Hadrian.
Reagan used the phrase to describe his military plans in the Cold War. The phrase has appeared in every Republican Party platform since 1980.