Editor's note: This is a developing story and is being updated.
NATO Secretary-General Jens Stoltenberg arrived in Kyiv on April 29 for a previously unannounced visit.
Stoltenberg's third visit to Ukraine since the beginning of the full-scale Russian invasion took place amid a deteriorating situation on the battlefield.
The NATO secretary-general said earlier that the almost seven-month delay in U.S. assistance for Kyiv "has had real consequences."
Due to the lack of artillery shells and air defenses, Ukraine lost a key front-line city of Avdiivka in February and retreated west from the villages of Berdychi, Semenivka, and Novomykhailivka in Donetsk Oblast in late April.
President Volodymyr Zelensky said he and Stoltenberg discussed further cooperation between Ukraine and NATO and "the real unification of our forces."
"Ukraine and the alliance have reached the highest level of relations since our independence, but not the highest possible," the president said.
During a press conference in Kyiv, Zelensky said that the two also discussed an initiative to set up a special fund for financial support for Ukrainian defense worth 100 billion euros ($107.1 billion) for a period of five years.
"Allies do have the opportunity to realize such an initiative. The details are very important to us, it is important that this is not at the expense of bilateral volumes, which are marked by our agreements on security guarantees," the president added.
Kyiv did not receive the much-desired invitation nor a firm deadline to join the alliance during the 2023 NATO summit in Vilnius, even though NATO took steps to tighten cooperation.
Stoltenberg invited Zelensky to join NATO's July summit in Washington, although U.S. Ambassador to NATO Julianne Smith said in February she did not expect the alliance to offer Ukraine a membership invitation.
"Ukraine’s rightful place is in NATO. Ukraine will become a member of NATO. The work we are undertaking now puts you on an irreversible path towards NATO membership, so that when the time is right, Ukraine can become a NATO member straightaway," Stoltenberg said.