I’m the Foreign Minister of Poland. Europe Has Got the Message.

I recently indulged in a guilty pleasure and rewatched “Independence Day,” the 1996 blockbuster movie about rapacious aliens trying to invade and plunder Earth. As I relished the visual fireworks — which, by the way, have aged well — one scene made me think about the real world.

Once Jeff Goldblum’s geeky scientist has figured out how to penetrate the magnetic shields of the huge, hostile spaceships, Americans rally the whole world to strike back. “About bloody time,” a British officer says. “What are they planning to do?”

The scene captured the spirit of the time. In the mid-1990s, we lived in a unipolar world in which the United States was the only unquestioned global power. In a moment of crisis, other nations expected America to come up with a solution. Thirty years later, those who turn to Washington looking for leadership might do so with less confidence.

In 2017, Mr. Trump spoke to thousands of Poles gathered on the streets of Warsaw. He told the enthusiastic crowd that “the trans-Atlantic bond between the United States and Europe is as strong as ever and maybe, in many ways, even stronger.” But, he added, “Europe must demonstrate that it believes in its future by investing its money to secure that future,” because “the fundamental question of our time is whether the West has the will to survive.”

As some allies grow weary of American power, Americans seem to be growing weary of their allies. For years — in his first term and in his recent campaign — President Donald Trump has been clear that he will put America first and has repeatedly reminded other members of NATO that the alliance is not a free ride.

Europeans finally got the message: Our security is not a service provided by the United States. It begins with us. But European security independence does not have to be incompatible with close collaboration with the United States. In an ideal world — in a safer world — there will be both.