[mattchamb]

What if a world leader said something along the lines of.. "Just ordered a strike xxxcountry. This is war."

That would probably trigger war.

[smitty1e]

Would it? Is there any country whose leaders are so foppish as to believe what they read on Twitter as though it were some actual diplomatic channel, or even an early warning system?

Color me skeptical, sir.

[SturgeonsLaw]

I'd wager you're correct in your assumption that most decision makers would not be duped by something like that, however a bogus tweet from an official source could be used as plausible cover for leaders who are seeking justification to take actions they wanted to take anyway.

Can you imagine what would have happened if a post-9/11 Iranian leader's account had tweeted "we have successfully acquired nuclear weapons and will be attacking Washington DC and Jerusalem tonight"? Elements within the governments of the USA and Israel have been agitating for war with Iran for decades, and that could give them the cover they need to act on it.

[smitty1e]

So, if all that's sought is a pretext, why don't state actors just hack accounts and stage pretexts at will?

The elevation of social media to the level of a United Nations general assembly just doesn't seem to pass muster, boss.