Opinion of US Entry into WWI

[The Mikado]

And it is undeniably true that none of the belligerent nations joined in the bloodbath to protect their overseas Empires, however important they were in other respects. They would all have been much better protected by neutrality.

I'd make Japan an exception...not in a desire to defend their empire, but they joined the war in a blatant push to claim all of Germany's Asian colonies while the Germans were distracted and couldn't fight back.

[The Mikado]

There was no credible chance of USA siding with the Central Powers, and the German attitude towards unrestricted submarine warfare and its inherent strangling of what was a very export-minded commercial economy meant that the USA and Germany weren't going to be on friendly terms.  Neutrality was a very difficult tightrope indeed.  The most obvious step towards the US remaining neutral would be for Arthur Zimmermann to not send a boneheaded message to Mexico City, but given how high tensions were running over the unrestricted submarine warfare and its implications on the US economy I doubt even that would have been sufficient.