Good question!How to get the US to join the war on the German side?
Here is one idea:
Let's say the the USA is totally unwilling to have her trade impacted by yet another European war, and decided to impose a matching materials export and merchant ship inspections for ships trading with Europe, so all ships in North American waters are allowed to carry only things the UK will allow neutrals to carry to the CP/ non-combatant nations, until such time as these restriction are lifted?
Basically, the USA decides that what is good for the goose, is also good for the gander, and that for as long as the UK is violating neutral rights, they loose exactly the same rights to trade in north american waters, until such time as they cease and desist interfering with other nations trade.
Obviously, this is not something that the UK is going to want to have happen, and they surely will not like it, nor be willing to tolerate a reciprocal restriction on her own trade.
From the UK perspective, the US upstarts are just asking for a beat down, while from the US perspective, it is the overbearing UK that is being unreasonable, and they must accept the US counter restrictions, as they are only fair after all, and of course this will simply end with the restrictions on both side being quickly dispensed with, and business will return to normal once the UK is made to see reason.
Of course, the best laid plans...
How does this work for folks?