The meaning of words can quickly change especially through the centuries.
Maybe a diplomatic ship isn't explicitly designed to conduct gunboat diplomacy, but there's no reason to avoid heavily arming a diplomatic ship, given how things are at the moment. Over potential member-states, a visible symbol of the dangers of the galaxy and a practical contribution to a potential defense of the world. When visiting our peers, a reminder that for all we enjoy peace, our vessels are modern, lethal combatants (please forget about the early 23rd century).
Sure, but that's not what the term "gunboat diplomacy" means.
Gunboat diplomacy is the pursuit of diplomatic objectives (usually but not always foreign policy) via displays of naval power to imply a threat of war or war actions if demands are not met. There's no reason whatsoever it should be confined to 18th-20th century European/American actions, because it wasn't confined to them once other nations saw its effectiveness and started copying it. Hell, if we're glossing over the most trivial of semantics, gunboat diplomacy was being performed by nations long before the term was coined.
Better hope that our diplomats can sell water to fish then, because even if you don't say it out loud parking a battlecruiser over unaligned planets, even a really big flashy one with a botanical garden and pool, will never be totally unthreatening.
You want imperial timeline go to the Confederation or the Terrans. The Federation is never going to roll up and say 'join us or we phaser your cities' or demand trade concessions. Or any of the other things Gunboat Diplomacy means.
Okay, let me break it down a little bit. Gunboat diplomacy is not "I have a very powerful ship in orbit while I do diplomacy", and it's not even "my diplomacy ship is well-protected". That's fine, and the second one is frankly just common sense in a Trek universe.
So as an example, Sisko blasting the Maquis with tricobalt torpedoes to make them vacate the planet is not gunboat diplomacy?
Sisko committing ecocide to force secessionists to surrender is not exactly a shining example of Federation policy.
Is the only difference whether or not you actually shoot, then?
As far as the Klingons are concerned, any diplomats worth their salt will be capable of throwing down with the best of them. Ensuring diplomatic overtures are backed with
The difference is whether you're using a threat of force, or actual force, for diplomatic concessions with someone you aren't at war with. Defensive war is fine. Defending your allies is fine. Countering influence of other imperial powers like the Klingons is fraught, but at least potentially fine. That's not what we're talking about.
That's actually pretty useful, thanks. Final two questions along those lines, then - IIRC the guy Sisko was chasing when he did that, Michael, was using chemical weapons on Cardassian civilians and was determined to kill every Cardassian colony in the demilitarized zone. Do we know if the colony that got tricobalt-ed was harboring Michael knowingly, and if so does that make them a war target in this instance?
And then you find a way to duplicate all of that in (nearly) every possible life-sustaining combination of biochemistry, temperature, atmospheric composition and pressure, and accompanying microbiome, for the widest possible range of species sizes (there is current precedent for hundred-ton sapience on Earth, after all, given the cetaceans), while additionally making mirrored holodeck(s) out of a very large fraction of that volume, so that the species in the 1-atm-oxy-nitro-breathers in one set of conference rooms can interact "normally" with the 300-atm-methane-breathers in the reconfigurable conference rooms.
Sounds like a job for the Federation-class Dreadnought!
