This image (and the close up below) of Donald Trump and Angela Merkel was taken at the recent G7 Summit in Taormina, Sicily, Italy.
Angela Merkel's expression is very much worth nuancing. Note that her central forehead is contracted and elevated along with her inner (medial) eyebrows. There is also significant tension of her lower eyelids. From a nonverbal perspective, when an Elevated Central Forehead Contraction (Elevated CFC) occurs - it's of profound significance. However, the CFC must always be correlated with "what the rest of the face is doing" - particularly the mouth.
We can see that, simultaneously, Merkel's jaw is "hanging open" - in what is often colloquially referred to as a "Slack Jaw". Notice too, that it's not widely open as it is displayed during sincere surprise, rather only mild-to-moderately so.
It's also important to point out that none of her teeth are visible.
Another detail which correlates with the sincerity of this moment (and the "Slackness" of the jaw) is that her jaw (mandible) is retracted backward (posteriorly). This gives the appearance of a (momentary) over-bite (less noticeable, however, because no teeth are visible). The value of this subtle yet significant finding cannot be overstated when assessing sincerity and emotional shock.
This is the face of emotional shock and emotional processing. Chancellor Merkel is feeling a form of grief and emotional pain. She's having difficulty wrapping her logical-rational mind around her emotions in her response to what Trump is telling her.
Summary: Angela Merkel is bewildered and astonished at what Donald Trump is saying to her. This is not political posturing - rather her emotions are sincere.
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