US and Ukrainian officials said they made substantial progress in two days of talks aimed to bring an end to Russia's invasion closer, with Washington reportedly offering Kyiv security guarantees modeled on NATO's Article 5 mutual defense pledge. While questions remained about key issues, including the fate of territory that Kyiv continues to hold in the eastern Donetsk region, US President Donald Trump said it appeared as though a deal to end Europe's largest and deadliest conflict since World War II was closer than ever. "We're trying to get…