AP could charge an extra fee for delivery of O/S parcels to be paid by the recipient and still remain within the terms of UPU aggreements (as could the USPS).

I'm unsure about the new agreement that came into force this year, though previously, Aus, NZ and Canada had reserved the right to amend terminal dues at their own discretion.

All countries are bound by the UPU convention which was updated this year and will run for the next 3 or 4 years?

What Trump is proposing is for the US to actually pull out of the agreement entirely.

That's a horse of a much different colour as the the UPU is a UN body, so it's a bit like saying they (the US) want no further part of Human Rights agreements or Arctic/Antarctic Exploitation Treaties etc.

How the US could actually make the system work is a bit of a mystery as China Post is subsidised by the Chinese govt so who would accept the proferred bill for parcel delivery ie a revised bill for terminal dues?

That being said, the UPU does have provisions in place to supposedly control below cost subsidisation of outbound postal charges.

Trump does have a point that the Chinese are playing fast and loose with the terms of the existing UPU agreement.

He should remember his history though; it was high tariffs and trade barriers that were the main cause of Japan's involvement in WWII on the opposing side.

They had been allies against Germany in WWI.

I'm not saying postal charges will lead to global warfare but as Trump continues to lean on China, they are busily patching up relations with their old enemy Russia (who hold their rear) while fortifying the Sth China sea (their front) and rapidly (and massively) expanding their navy.

Interesting times indeed.