The Donald Trump administration no longer sees the United States as a guarantor of European security. This will have major repercussions for the war in Ukraine, for Russia’s imperial ambitions, for the defense of NATO’s eastern front, and for stability in the Western Balkans.

In speeches delivered by US officials and comments by Trump himself, Europe has been told to stop relying on the US for its security. The White House is thereby challenging Europe to invest in its own defense, as most European states have failed to build the military capabilities necessary to deter and defeat Russia in a conventional war. Poland and other states directly confronting Moscow have been warning for years that the West must seriously ramp up its militaries, as the potential for armed conflict with Russia is mounting. Trump’s threatened withdrawal from Europe has confirmed their fears.

Trump’s and Vice President’s Vance's public attack on Zelenskyy in the Oval Office indicated that they are becoming increasing desperate to make any deal to end the war in Ukraine so that Trump can appear as a winner and claim the Nobel Peace Prize. Evidently, Putin’s officials have told their US counterparts that they will not withdraw from any Ukrainian territory under Russian occupation. Hence, Trump is now leaning heavily on Zelenskyy to make major concessions. However, Trump has also exposed himself to a major failure because Kyiv will not surrender to Moscow and support for Zelenskyy in Europe and Ukraine itself is likely to soar.

If Trump abandons Ukraine, he will go down in history both as a Russian asset and a geopolitical loser. Nonetheless, the negotiation process launched by the White House has no certainties and Trump could even turn against Russia if he feels that Moscow is denying him a “peace victory.” Russia itself is a declining power as evident in its poor military performance, collapsing energy revenues, and depleted budget. Putin may view Trump as a lifeline to save the Russian state from collapse and military defeat. But Russia’s escalating weaknesses may make Washington realize that Moscow is bluffing about its capacities.

It is obvious that there will be no durable deal between Kyiv and Moscow until the Russian army withdraws from Ukraine. Russia will not stop its aggression until it seizes all the regions it has already integrated in its constitution, while Ukraine will not stop its counter-offensives until it has regained all of its occupied territories. Trump may be able to arrange some temporary ceasefire and claim victory for ending the war, but everyone remembers how long ceasefires lasted in ex-Yugoslavia. There was no final resolution to the war until the Serbian army was defeated and the security of newly emergent states was guaranteed.

Most major European leaders, including the incoming German Chancellor Friedrich Merz, now understand that Russia is the main danger to peace in Europe and it is essential that it be defeated in Ukraine. Europe must focus above all on its security, with much higher defense spending, a ramping up of military production, and an expansion of military units prepared for war with Russia. This must begin with a massive infusion of weapons to Ukraine. Trump’s threats to cut off military aid to Kyiv is ringing alarm bells in European capitals and NATO allies minus the US must fully commit to Ukraine’s victory by taking America’s place in delivering weapons and other resources to Kyiv as rapidly as possible.

European leaders must also be prepared to step in to conduct new “peace talks” between Moscow and Kyiv if the Trump led discussions end in failure. A substantial increase in weapons supplies to Ukraine and complete energy sanctions on Russia will provide the European coalition with much stronger leverage vis-a-vis Moscow. And Ukraine will continue to exert military pressure in decimating Russian forces and bombing energy and military targets inside Russia.

If Trump’s trans-Atlantic policy results in a withdrawal of security guarantees to NATO allies, then the “European pillar” of NATO must assume a European command. This cannot be an EU army, which duplicates NATO capabilities, creates new layers of bureaucracy, and undermines the national sovereignty of individual states. And it must include a coalition of all willing security contributors, including key non-EU countries such as the United Kingdom, Turkey, and Norway. NATO will then be transformed into a Europe-centered security alliance and can include new states that are willing to commit to mutual defense. It is also important to remember that the Trump administration is temporary and a future US government may decide to fully re-engage in Europe’s defense. This would contribute to another North Atlantic security transformation.

No “international order” is permanent. Alliances, politics, strategies, and policies are constantly in flux and almost every generation in Europe has faced a major war, whether generated by internal or external imperial powers. Europe needs to make certain that Russia’s attack on Ukraine is the last attempt at violent re-imperialization on the continent.

All NATO members must contribute to the pan-European imperative to defeat Russia in all domains, and not only on the battlefield. A militarily resurgent Europe can also provide fresh momentum to the EU project in which the West Balkans will be on the front line for membership. They must also prevent another Balkan war that Moscow would gladly encourage while the Trump administration remains on the sidelines. Belgrade and Banja Luka will be looking at the trans-Atlantic rift as a unique opportunity to pursue their own pan-Serbian agenda, calculating that Trump will favor Russia’s designs on the peninsula. It is now up to the pan-European alliance to act firmly and with muscle to defeat the external and internal adversaries of state independence and civil democracy.

 Janusz Bugajski is a Senior Fellow at the Jamestown Foundation in Washington DC and author of two new books: Pivotal Poland: Europe’s Rising Power and Failed State: A Guide to Russia’s Rupture