Russia reserves the right to use nuclear weapons in the event it faces aggression by Western countries, Moscow's top security official, Sergei Shoigu, was quoted as saying in an interview with the TASS state news agency on Thursday. Shoigu's comments come as U.S. President Donald Trump and Vice President JD Vance have warned that Washington could walk away from trying to negotiate a peace settlement in Ukraine if there is no progress on a deal soon. Since taking office in January, Trump has upended U.S. policy toward the three-year-old war, pressing Ukraine to agree to a ceasefire while easing pressure on Russia.