Ukraine’s bid to fast-track its efforts to join NATO, following Russia’s annexation of four more Ukrainian territories, is being met with caution in Brussels and Washington, where top officials are trying to shift the focus to their unwavering support for Kyiv.

Ukrainian President Volodymyr Zelenskyy posted video to social media Friday that shows him signing a formal bid for an accelerated membership with the Western alliance.

“De facto, we have already made our way to NATO,” Zelenskyy said in a statement that accompanied the video. “Today, Ukraine is applying to make it de jure.”

But when asked during a briefing whether the alliance would move quickly on the application, NATO Secretary General Jens Stoltenberg demurred.

“Our focus now is on providing immediate support to Ukraine, to help Ukraine defend itself against the Russian brutal invasion,” Stoltenberg told reporters.

“That is the main focus and the main effort of NATO allies as we speak,” he added, saying such support would be forthcoming “for as long as it takes.”

Officials with NATO and NATO member countries have long said that sovereign nations, like Ukraine, should have the freedom to seek membership in the alliance. And this past June, Ukraine attended a NATO heads of state and government summit in Madrid.

There has been no rush, however, to grant Ukraine full membership.

“Our view is that the best way for us to support Ukraine is through practical on the ground support in Ukraine, and that the process in Brussels should be taken up at a different time,” White House National Security Adviser Jake Sullivan told reporters Friday.

Russia has repeatedly called the possibility of NATO expansion an existential threat, while arguing prior to its invasion of Ukraine in February that Ukrainian membership in NATO would be a provocation.

Western and U.S. officials, though, argue Russia’s actions have had the opposite effect, with Sweden and Finland moving to join NATO in July.

The U.S. Senate approved NATO membership for the two countries in August. Only Hungary and Turkey still must ratify their applications for membership.