Some of the President-elect's most pointed comments were aimed directly at her.
First and foremost, there was the direct attack on Merkel's decision to open German borders to refugees
. Normally political leaders steer well away from making any observations about the domestic polices of their allies.
On this occasion, characteristically, the President-elect jumped in with both feet.
"I think she made one very catastrophic mistake and that was taking all of these illegals, you know taking all of the people from wherever they come from. And nobody even knows where they come from," Trump said in an interview with the Times of London and the German publication Bild.
At any time for any politician to say this -- particularly the inaccurate claim that refugees are illegal -- would be a powerful intrusion into German politics. In an election year, for this to be said by the man who will be President of the United States in a matter of days, is electoral dynamite.
Somewhere in an Alternative für Deutschland (AfD)
office this quote is being worked up into a leaflet with "catastrophic" and "illegal" in giant, bold, italics.
Worse, in the long term, is the aside about the European Union:
"You look at the European Union and it's Germany. Basically a vehicle for Germany. That's why I thought the UK was so smart in getting out."
Where does one start disagreeing with this? One might think that a history lesson about this as a Franco-German project would be a good idea. However, as so often with the Trumpian stream of consciousness it is an immensely revealing remark.
The President-elect sees the world in some parody of the 19th century conception of the great powers. There is the US and Britain, and then Russia and finally Germany. Foreign policy is about balancing them all against each other. That's the context for understanding his remark about Merkel and Russian President Vladimir Putin.
"Well, I start off trusting both — but let's see how long that lasts. It may not last long at all."
The casual equivalence of one of the world's largest economies and most significant democracies with an effective autocracy whose economy is only a quarter its size when judged by GDP per capita is insulting enough in itself.
When you consider that President Obama suggested just last November that if he were German then he might vote for Mrs Merkel
, it is all the more devastating.
This should be taken together with what Mr Trump said on NATO, which is worth quoting in full
"I said a long time ago -- that NATO had problems. Number one it was obsolete, because it was, you know, designed many, many years ago. Number two -- the countries aren't paying what they're supposed to pay. I took such heat, when I said NATO was obsolete. It's obsolete because it wasn't taking care of terror. I took a lot of heat for two days ...
"And the other thing is the countries aren't paying their fair share so we're supposed to protect countries but a lot of these countries aren't paying what they're supposed to be paying, which I think is very unfair to the United States. With that being said, NATO is very important to me ...
"There's five countries that are paying what they're supposed to. Five. It's not much, from 22."
Read in its broad sweep, that sends two specific messages. On the one hand, a handful of NATO members need to spend more on defense -- matching their commitment to 2% of GDP.
On the other, NATO needs to have a more forward leaning posture with regards to terrorism. So far, so reasonable. Yet neither message qualifies the brutal observation that the alliance is "obsolete," and we know that what is obsolete is replaced rather than reformed.
Why should all of this concern Merkel? Since the election of Donald Trump in November of last year, much has been made of the fact that she is last leader of her generation still standing
With a US President-elect signaling that he could abandon European defense co-operation and the UK obsessed with Brexit above all other things, the burden of upholding Western, liberal values and European strategic security rests on her shoulders.
That would be difficult enough in normal times; to do so in in an election year while populism seems to be stampeding across the continent could be enough to finish off liberal Europe's last hope.