EU leaders will grapple at a summit on Thursday with how to get more weapons to Ukraine's outgunned forces while also re-arming their own countries to face Russia's Vladimir Putin -- aggressive and newly emboldened after cementing his grip on power.
Over two years into Moscow's all-out war against its neighbour, Kyiv's troops are struggling to hold back the Russian army as Western support fails to keep pace with the fighting.
"If Ukraine had to surrender, then a puppet regime will be installed in Kyiv, the Ukrainian people will be crushed," EU foreign policy chief Josep Borrell warned ahead of the Brussels meeting.
"The Russian army will be at our borders and we could be sure that they will not be stopping there."
Following his weekend presidential election success, a bullish Putin on Wednesday described it as a "prologue" to victory in Ukraine.
Kyiv desperately needs more weapons and ammunition to fend off Putin's troops, who have made recent battlefield gains.
As a $60-billion package remains stalled in Washington, the EU's 27 leaders will debate a plan to spend profits from 200 billion euros in frozen Russian central bank assets on weapons for Ukraine.
Officials said that the proposal could unlock some three billion euros a year for Kyiv and that if EU countries agree quickly, the money could start flowing by July.
That would come on top of more than 33 billion euros that the EU says it has provided towards arming Ukraine since the Kremlin invaded in February 2022.
Alongside the efforts to get more weapons to Kyiv, the EU is also frantically working on ways to boost Europe's defence industry to be able to arm Ukraine and build up its own forces.
Brussels has put forward a raft of proposals aimed at ramping up capacity but there are complaints that Europe is still not moving fast enough.
While Russia has put its economy on a war footing, the EU has fallen well short of a promise made last year to supply Ukraine with a million artillery shells by this month.
Meanwhile, the Czech Republic has spearheaded its own initiative aimed at hoovering up hundreds of thousands of shells available around the world to send to Kyiv.
"At this crucial moment in global history, we must be defence-ready, matching the urgency of the threat," European Council chief Charles Michel wrote in an editorial.
"If we want peace, we must prepare for war."
France, Estonia and Poland have pitched the idea of using joint borrowing similar to the massive package of support the EU came up with during the Covid pandemic to now fund defence spending.
But a majority of member states -- led by the so-called "frugal" countries such as Germany -- are unwilling to go anywhere near that far.
Instead, the discussion will likely focus on getting the EU's lending arm, the European Investment Bank, to expand its funding for the sector.
At the moment, the bank is limited to investing in only a small number of "dual-use products" that can have both military and civilian functions.
While the response to the conflict in Ukraine will dominate much of the summit, EU leaders will also push for a united stance on the war in Gaza, with United Nations chief Antonio Guterres in attendance.
Diplomats say that an overwhelming majority of countries support a call for an "immediate humanitarian pause" in Israel's offensive and a warning for it not to launch a ground operation in Rafah.
But staunch Israeli ally Hungary has repeatedly blocked efforts to take a tougher line and could veto a consensus this time as well.
Closer home, EU leaders look set to give the green light to opening membership negotiations with Bosnia as Russia's war has sparked a push to expand the bloc.
Diplomats said that the Balkan state would likely get an agreement on launching talks, but they could only start in earnest when the country has passed more reforms.
