Freight Cost Explosion

The US Postal Service (USPS) has left us scratching our heads. Without warning the cost of all overseas mail from America has been trebled - yes, you read it rightly. It seems they are now sending everything by air. The knock on effect is that the cost of US published books in this country is likely to increase. It is hard to judge just how much in the longer term because international carriers like UPS, DHL and Fedex for example are swooping in to get a slice of the cake. This should moderate the effect, but it is still going to be painful. Our own intention is to absorb as much as we possibly can on the Gospel Mission books we distribute.
I would genuinely like to be given a reason for the USPS decision. It seems crazy. What's suddenly wrong with ships? Do they want to make their carbon footprint smudgier than ever for the sake of it? Can anybody enlighten me pleeeeeease?
Jeremy