Here are a few options for a formal title, depending on the specific focus:
Option 1 (Most formal and journalistic):
EU Foreign Service and Ukrainian Agency Uncover Russian Disinformation Campaign Aimed at EU Bid
Option 2 (Direct and authoritative):
EU and Ukrainian Authorities Expose Russian Efforts to Undermine Ukraine’s EU Accession
Option 3 (Concise and professional):
EU-Ukraine Joint Report Exposes Russian Subversion of Ukraine’s European Integration Efforts
Recommendation:
Option 1 is the most standard for an international news or policy briefing format.