"express your displeasure"
It isn't as simple as that. Using the word "displeasure" is to gloss over the disastrous fallout that will resonate around the world over the "bad things" he does. America can right it's own ship on the domestic level when we have to. However, it takes years of delicate diplomacy to restore the faith of the world in America's leadership once that trust has been destroyed.
Our allies started expressing their concern long before Trump was elected. They're well aware that a pariah like Trump can, and probably will, upset the balance of relationships that have been years in the making.
America has done a terrible thing. Up until now, America's dependability has been the backbone of the world. Trump's lack of stability is now what represents America and the world is justifiably nervous. Mistrust is contagious. It spreads like wildfire.
When the Trump era is over ~ and it will be eventually ~ how does one go about apologizing to the entire planet for bringing this plague down upon it?