Letting Ukraine into the EU will reinforce, not undermine, Europe’s security | Piotr Buras and Engjellushe Morina

Many Europeans fail to realise that EU enlargement is the only way to counter Russia and China - but this week, leaders must act

• Report: Europeans open to Ukraine joining EU, survey shows before key summit

The Ukrainian counteroffensive has stalled. For the first time since the outbreak of the war, the feeling that Russia may actually be winning is taking root. The long-applauded western resolve in support of Ukraine is waning. The western Balkans are broiling. And next year's presidential election in the US does not bode well for Europe. In this context, the timing of the summit of EU leaders on 14-15 December could make it the most consequential in the bloc's recent history.

For EU leaders, there is pressure to open accession negotiations with Ukraine and Moldova and agree a 50bn package of financial help for Kyiv - and they would be well advised not to underestimate the gravity of these two decisions.

Piotr Buras is the head of the Warsaw office at the European Council on Foreign Relations (ECFR). Engjellushe Morina is a senior policy fellow at ECFR