Vice-president tells rally in battleground Pennsylvania that former president will violate oath of office again if re-elected in November

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US Deputy Secretary of State Kurt Campbell said Washington was looking into reports that North Korea was sending troops to fight for Russia against Ukraine.

Western countries have long accused North Korea of sending weapons to help Russia fight in Ukraine. On Wednesday, Ukrainian President Volodymyr Zelenskyy said the North was also sending personnel, becoming effectively a participant in the war.