<p>This paper analyzes how Europe handles U.S.–Russia relations against the backdrop of the Russia–Ukraine conflict. When Donald Trump returned to the White House in 2025, his neutral stance on the Russia–Ukraine conflict plunged Europe into unease. Europe has become a “constant” in “supporting Ukraine and opposing Russia,” as evidenced by its ongoing aid to Ukraine and sustained pressure on Russia. The reasons for Europe’s stance include its adherence to the international rule of law, geopolitical fears of Russia, and distrust of Putin. To mitigate the “U.S. variable,” Europe, despite internal divisions, has mainly adopted strategies to win over Trump: coaching Zelenskyy to improve his attitude toward the U.S., committing to take on the main financial and security responsibilities for Ukraine, and complying with the U.S. on NATO military expenditure sharing and the U.S.–EU Free Trade Agreement. Meanwhile, Europe has also taken steps toward achieving strategic autonomy, such as proposing the “Re Arm Europe” plan and boosting military industrial capacity. However, it remains unable to fill the gap left by a potential U.S. withdrawal in areas like disruptive defense technologies. Overall, Europe still remains committed to aiding Ukraine and opposing Russia; however, it faces numerous internal and external challenges that may lead to higher costs associated with the Ukraine crisis in the future.</p>