Foreign ministers from Estonia, Latvia and Lithuania said they would welcome Ukraine's accession to NATO "as soon as possible" after the country formerly applied to join the alliance on Friday.
Urmas Reinsalu (Isamaa), Edgars Rinkevičs and Gabrielius Landsbergis all posted the same message on social media, which said: "Ukraine's Baltic friends fully support welcoming Ukraine into NATO as soon as possible. Ukraine's inspirational bravery can only strengthen our alliance."
This was followed by a row of emojis showing the flag of each country, a red heart, a Ukrainian flag, and a sunflower.
All three countries have pushed for Ukraine to join both NATO and the EU in the past. The Baltics joined the alliance in 2004.
On Friday evening, the Ukrainian government announced it had officially applied to join NATO under an "expedited procedure".
"We trust each other, we help each other and we protect each other. This is what the Alliance is. De facto. Today, Ukraine is applying to make it de jure," President Volodymyr Zelenskyy said during a video address, Politico Europe reported.
The announcement came hours after Russia annexed four regions in eastern Ukraine.
NATO Secretary-General Jens Stoltenberg on Friday evening reiterated the alliance's unchanging position that it is open to new members but shied away from directly endorsing Ukraine's bid, Politico Europe wrote.
"Every democracy in Europe has the right to apply for NATO membership and NATO allies respect that right, and we have stated again and again that NATO's door remains open," he told reporters in Brussels.
Editor: Helen Wright