Did Ukraine officially join NATO on May 16, 2023? No, that's not true: Ukraine is not part of the North Atlantic Treaty Organization and it didn't join NATO on May 16, 2023. On that day, Ukraine officially joined the NATO Cooperative Cyber Defence Centre of Excellence (CCDCOE).
The claim appeared in a video (archived here) published on TikTok on May 16, 2023, by the Account @trzh2, Просто чел с тик-тока ("Just a TikTok dude," translated into English), after the national flag of Ukraine was raised at the Headquarters of the NATO Cooperative Cyber Defence Centre of Excellence in Tallinn, Estonia, on May 16, 2023, marking official accession of Ukraine to the CCDCOE, together with Iceland, Ireland, and Japan.
This is what the post looked like on TikTok at the time of writing:
(Source: TikTok screenshot taken on Tue May 23 11:07:58 2023 UTC)
The video opens with the graphic, in Russian:
16.05.2023 Украина вступила в НАТО. Видео поднятия украинского флага в Брюссели
Translated by Lead Stories staff into English, the text reads:
05.16.2023 Ukraine joined NATO. Video of raising the Ukrainian flag in Brussels
On May 16, 2023 Ukraine has officially joined the NATO Cooperative Cyber Defence Centre of Excellence (CCDCOE) together with Iceland, Ireland and Japan. For the occasion, Ukrainian, Icelandic, Irish and Japanese flags were raised near the headquarters of the centre located in Tallin, Estonia, and not in Brussels, Belgium, as claimed in the video' caption.
In early March last year, representatives of 27 NATO member states decided to give Ukraine the status of a member country of the NATO CCDCOE - before that, Ukraine's membership was blocked by Hungary.
Located in Tallinn, Estonia, CCDCOE is a NATO-accredited cyber security centre and think tank specialising in interdisciplinary applied research, analysis, information exchange, and cyber defence training and exercises.
"We thank the CCDCOE Sponsoring Nations for inviting Ukraine and express our special gratitude to the Government of Estonia for their support and assistance on the way to NATO CCDCOE!" the Foreign Ministry of Ukraine said after the ceremony.