I'm sure the Navy is really enjoying their new toy and will have lots of fun playing with it, but I honestly don't think it will change politics much. For most

I'm sure the Navy is really enjoying their new toy and will have lots of fun playing with it, but I honestly don't think it will change politics much. For most countries in the world, there is little practical difference between a navy ship 30 miles off their coast with a railgun, and a navy ship 30 miles off their coast with cruise missiles. Even if they could shoot down the cruise missile (which most countries couldn't do with much reliability), the fact that the cruise missile was flying through their airspace in the first place implies active military conflict. That's a situation that already escalated beyond diplomacy. Think of it this way: Which countries would shrug off the US threatening them with stealth bombers and cruise missiles, but wouldn't shrug off the US threatening them with a railgun? Russia or China? Maybe France or the UK? Just about any country that plausibly might be in a position react that way is a nuclear power anyway.