War. No doubts. Not because treason or similar, but because Confederate expansion plans (Golden Circle) and Anglo-French actions in American Continent are an existential threat to US interests.
So this is my opinion about superpowers's positions, circa 1914, about incoming Mexican Revolution:
United States "What hell Richmond think to do? To stole our territory?!? Never! It's time that Uncle Sam give a lessons to these confederate asses"
Confederate States "Yes, we're able to stabilize South West! Now we have to move quickly towards West to get a strategic port on Pacific Ocean.... One moment... Madero took Mexico City??? Oh Dear God, it's a tragedy!"
Canada "Sssss.... Shut up, Quebec! If you stay still, Americans can not see you. At least I hope..."
United Kingdom "Panama is mine! We have to find a way to put the region in our hands! With good manners...or with bad ones! Meanwhile we could begin to mobilize our fleet in Caribbean Sea: Mexico will be weak..."
France "It's the last time that we give a fucked crutch to these incompetent Mexicans, them and their stupid Empire! Confederates have not take that damned city! Oh oui, now we're their allies, merde..."
Japan "These stupid western devils have to ruin always everything! Right now, we have just succeeded to put Hawaii in our hands... Now we should respect our alliance with Great Britain... Yeah... But what if..."
Others South American nations "Fight! Fight! Fight!"
Germany "Sell weapons and smile, boys! They wanted do the party without us"
Russia "Why Alaska doesn't work, sigh?"
Austria "Serbia will be destroyed, nothing else matters, mwhahahahah!"
Spain "My poor colonial empire..."
China "Zzzzzz... The client you called is busy with all-against-all civil war, please try later"
Italy *He looks at all that look themselves askance, whistling and smiling, with a rifle behind his back, unloaded*
Switzerland "Not my business"