Iran is under sanctions from the United States. So France, the United Kingdom, and Germany decided to set up a partnership to bypass the sanctions. Now 8 more European countries decided to bypass the US sanctions.
When President Trump ended the betrayal from Obama he did this without any support from other countries. He promised to hurt the Iranian economy very hard. This all to ensure Iran will not develop a nuclear weapon.
The European move is an indication that US dominance is coming to an end. If you think about this we need to consider what President Trump will do. Will he also impose sanctions against European countries trading with Iran?
The United States is more and more standing alone when it comes to Iranian matters. The big question is what the hardliners will do and how Trump will respond to Europe.