Ukrainian President Volodymyr Zelenskyy has urged the United States to provide more ammunition for its Patriot air defense systems to counter Russian ballistic missiles, according to a document reviewed by AFP on Wednesday.The appeal underscores Ukraine’s almost total reliance on its Western allies to down Russian missile barrages, despite having pioneered a system for intercepting long-range drones that is the envy of some of the world’s most advanced militaries.For the latest updates on the Russia-Ukraine war, visit our dedicated page.The request comes just days after one of the worst combined missile and drone attacks launched against Kyiv since Russia invaded Ukraine more than four years ago, which wrought devastation across the capital.In a letter dated May 26 and addressed to President Donald Trump, Zelenskyy asked Washington to “help us secure this vital tool of protection against Russian terror - Patriot missiles PAC-3 and additional systems - to stop Russian ballistic missiles and other Russian missile attacks.”Zelenskyy conceded in the five-page document, which was also addressed to Congress, that: “when it comes to defending against ballistic missiles, we rely almost exclusively on the United States.”“And it is in Ukrainian hands that Patriot systems have proven something extremely important: The majority of Russian missiles can be stopped,” the Ukrainian leader added.Zelenskyy’s appeal comes at a turbulent moment in ties between Ukraine and the United States.Trump re-entered the White House last year vowing to bring about a speedy end to Russia’s invasion - now grinding through its fifth year.But US-led efforts to bring Kyiv and Moscow back to the negotiating table have been derailed by the US and Israeli war with Iran, as well as a failure to make progress on key sticking points toward any peace deal, in particular who would control swathes of eastern Ukraine.Both sides have stepped up their long-range drone and missiles attacks since a series of bilateral talks mediated by the United States earlier this year appeared to stall.