Bloomberg Opinion — The yellow and blue flag of Ukraine, which was banned during the Soviet era, has become a powerful global symbol after the Russian invasion. It has flown in iconic locations from New York to Sarajevo, has been shared on social media and waved during anti-war protests around the world.

It has also done little to unite members of the European Union and the NATO alliance. This is a welcome moment for post-pandemic geopolitical solidarity that has hardened borders and national interests. Sanctions piled up against Russia, refugees were welcomed in many countries, business and political relations collapsed, and financial and military support for Ukraine increased.

As Ukrainian President Volodymyr Zelenskiy urges Europe to be more assertive, Russian President Vladimir Putin stirs up the kind of fear that breaks long-standing taboos. The European Union supplies arms to a warring country for the first time in its history, using an endowment whose name, the “Peace Facility”, says it all. It is not uncommon for safety to take precedence over economic comfort. The bloc faces “permanent instability” in the new normal, according to Bruno Lete of the German Marshall Fund.

And as Europe’s balance of power tilts to the East, where the Baltic states feel emboldened after years of warning of Putin’s hostility but also vulnerable to conflict at their doorstep, Kiev is reaffirming its demands for the ultimate prize: membership in the EU club. Tired of politely knocking on the door, Zelenskiy kicked it. “Europe must give Ukraine everything it asks for,” the Latvian Defense Minister wrote in an op-ed di Financial timeciting Ukraine’s aspirations to join the European Union as well as NATO.

Obviously, if there was a time to dream big, it was now. It is perhaps easier to imagine the EU flag waving with Ukraine one day than to NATO, which the former alliance secretary general described as a scenario that would never happen. Some signs of acknowledging Kiev’s European aspirations would be a worthy complement to more funding and deeper ties, especially if diplomatic pressure on Putin intensifies.

But in the midst of idealism, there must still be realism: not all taboos will be broken.

The expansion of the EU is not just bureaucracy, but a very well-guarded force that has become a divisive issue as much as defence, especially in the wake of Britain’s departure and concerns about democratic backsliding in the East. Ukraine’s 43 million citizens and a commodity-centric economy will take years, if not decades, to integrate. Even as European Commission President Ursula von der Leyen touted that Ukraine is “one of us,” European Council President Charles Michel warned of “different” opinions on the matter.

Nor is it clear that the Europeans have completely decided what kind of defense they want. There is a lack of political will, concrete budget commitments and the 27 countries’ inability to define their most pressing threats. The EU arms financing mechanism for Ukraine is an extra-budgetary intergovernmental tool that does not require any internal pressure. We’re still at the easiest point of change: the beginning.

Even without a comprehensive defense outlook, further spending seems inevitable. Defense stocks are up: BAE Systems (BA) and Thales (EPA) are up about 25% this month, and hitting the token level of 2% of GDP would see Germany alone spend an additional $18 billion, according to analysts at Jefferies. Even if Julien Theron of Sciences Po points out that the 2% figure is more symbolic than NATO wishlist fulfillment, a revival is brewing.

And the EU’s willingness to confront its trade and energy ties with Russia is an important signal for unity with a global dependency that makes it vulnerable: the recent launch of tools to monitor foreign investment from a power like China is slowly gaining traction.

Ultimately, governments and voters will set real boundaries for a firmer EU. What seems to unite today may have the opposite result tomorrow. Images of US troops leaving Afghanistan in disarray, or French troops leaving Mali, are visible signs that an initially popular and necessary military response could lose support over time. The European Union has not yet felt the full economic burden of the sanctions.

However, encouragingly, the EU’s power play is seen and not just heard: a more assertive bloc willing to invest in defense with US backing, face economic dependencies that leave it vulnerable, and find common ground among its members. This is an idealistic flag, but one that deserves to be flown.

These notes do not necessarily reflect the opinions of the editorial board or Bloomberg LP and its owners.