EU President Donald Tusk made a similar suggestion in May after Trump had pulled out of the Iran deal and the Paris climate agreement, threatened a series of trade disputes with Europe and constantly criticized NATO.
"Europe must do everything in its power to protect, in spite of today's mood, the transatlantic bond. But at the same time we must be prepared for those scenarios, where we will have to act on our own," Tusk said.
Tusk also said that the EU "should be grateful" to Trump "because, thanks to him, we have got rid of all illusions."
"Looking at the latest decisions of President Trump, someone could even think: With friends like that, who needs enemies?" Tusk said, later adding, "He has made us realize that if you need a helping hand, you will find one at the end of your arm."