KYIV, Ukraine (AP) — Ukraine's President Volodymyr Zelenskyy was in Sweden on Thursday for talks with Prime Minister Ulf Kristersson on bilateral defense cooperation, the Ukrainian leader and the Swedish government said.

The two countries are preparing “a major defense package” and working on a deal to provide Gripen fighter jets to Ukraine, Zelenskyy said on social media.

The Ukrainian leader has sought to deepen defense cooperation with other countries by offering the drone expertise his country has built up over more than four years fighting against Russia’s invasion.

Zelenskyy says Ukrainian specialists have helped countries in the Middle East — specifically the Gulf Arab region — strengthen their air defenses amid the Iran war. They have helped at American military bases in the Mideast as well, he says. Ukraine has also entered into joint drone production agreements with countries in the European Union, which fears that Russian President Vladimir Putin has military ambitions beyond Ukraine.

Ukrainian drones that patrol the 1,250-kilometer (780-mile) front line and strike deeper at supply routes have pinned back Russia's bigger army.

“Ukraine’s successful mid-range and front-line drone strike campaigns are limiting Russia’s ability to transport personnel to the front line and to supply and sustain front-line positions,” the Institute for the Study of War, a Washington-based think tank, said in an assessment late Wednesday.

Russia has occupied about 20% of Ukraine so far. That includes the Crimean Peninsula, which Russia seized in 2014. The cost of capturing that land has been huge, with the head of U.K.’s GCHQ intelligence agency saying Wednesday that almost half a million Russian soldiers have been killed in the conflict.

Russia, however, still has an edge in long-range ballistic missiles, which it has used throughout the war to damage Ukraine’s power grid and hammer cities.

Russian forces fired almost 90 missiles as well as hundreds of drones at Kyiv last weekend in an effort to overwhelm air defenses as part of its escalating long-range aerial campaign on civilian areas of Ukraine.

Zelenskyy has written to U.S. President Donald Trump and Congress asking for more American-made air defense ammunition to counter Russian ballistic missiles, Kyiv officials said Wednesday.

Ukraine needs more U.S. Patriot PAC-3 missiles and other air defense systems, Zelenskyy said in the letter, warning that deliveries to Ukraine are falling dangerously short as the Iran war diverts U.S. stocks.

The Ukrainian capital is bracing for further heavy bombardments. But no foreign diplomats are known to have heeded Moscow’s recommendation to leave Kyiv ahead of what the Russian Foreign Ministry said earlier this week would be “systemic strikes” on Kyiv.

The Ukrainian Foreign Ministry said Thursday that all diplomatic missions in the capital have continued operations.

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