Ukrainian President Volodymyr Zelenskiy has received a second big promise of military aid in as many days for his war with Russia during a whirlwind tour through the European Union.
The $US1 billion ($A1.5 billion) pledge for 2024 came from Belgium, which topped up the money with a commitment to give 30 F-16 fighter jets over the next four years.
"Our task is to use the first F-16 on the battlefield this year and in such way fortify our positions," Zelenskiy said on Tuesday.
The Netherlands added to the goodwill by promising to quickly assemble with key EU partners a Patriot air defence system, which Zelenskiy sees as key in stopping Russia from hitting his country's power grid and civilian areas, as well as military targets, with devastating glide bombs that cause wide destruction.
NATO chief Jens Stoltenberg welcomed the move but insisted much more work was needed. "We have seen some progress, but more progress and more air defence systems are urgently needed in Ukraine," Stoltenberg said as he headed into a meeting with EU defence ministers.
A day earlier, Zelenskiy signed a security agreement with Spain that allocates one billion euros ($A1.6 billion) of military aid to Ukraine in 2024, and five billion euros ($A8 billion) by 2027.
The bilateral aid is essential since the 27-nation bloc is again struggling to overcome Hungary's objections to the EU itself providing billions of euros in military aid to Kyiv, which is in its third year of war following Russia’s 2022 full-scale invasion.
An estimated 6.5 billion euros are stalled by the Hungarian government of Prime Minister Viktor Orban, who is considered Russia's staunchest ally in the EU. Single member states have wide veto powers and Hungary has long held up funds aimed at boosting Ukraine's defence efforts.
"That's the sad thing that we have the cash, we have the capacity, but we are still pending decisions to implement" aid decisions for Ukraine, EU foreign policy chief Josep Borrell said.
Zelenskiy met with Belgian Prime Minister Alexander De Croo on Tuesday, and as well as the immediate money, obtained a security agreement aimed at providing guarantees of military help until Ukraine joins the NATO alliance.
Since Russia launched a spring offensive around eastern Kharkiv, Zelenskiy has insisted Ukraine urgently needs seven more US-made Patriot air defence systems.
Dutch Defence Minister Kajsa Ollongren, meeting with her EU colleagues, said that such a system will be built "in a short time frame". The Netherlands has the core components for a Patriot system and other EU nations will contribute other key parts and munitions.
"Ukraine is also fighting Europe's fight," she said.
Zelenskiy was to visit Belgium and Spain earlier in May but postponed all his foreign trips after Russia launched its offensive in the Kharkiv region.
Ukraine has repeatedly tried to strike behind Russian lines, often with drones, though Russia's response to the new technology used in unmanned vehicles has improved in recent months.
The onslaught unfolding as the weather improves has brought Ukraine’s biggest military test since Russia’s full-scale invasion began.
Slow deliveries of support by its Western partners, especially a lengthy delay in US military aid, have left Ukraine at the mercy of Russia's bigger army and air force.
