EVERYONE gets their weaponry from the US (they bought it back when they were allies, now their enemies), and/or gets weaponry developed with US military R&D.
It's certainly good for the US defense industry. You've got to buy more better weapons cause your enemy has bought more better weapons, and both sides buy em from the US defense industry.
When the US gives another country military aid (or actually most any kind of aid), 100% of the funds 'donated' need to be used buying military goods from US companies. So military aid goes right to US defense companies too. (I think Israel is the one special exception, who for some reason only have to spend 50% of their military aid on US goods, and can spend the other half on Israeli-made goods).
The US spends more on the military than every other country _combined_.
So, yeah, I'm not sure this state of affairs could really be described as the US keeping the planet _safe_ by spending so much on military. But it is true that the US equips the entire rest of the world militarily.