"Before I even arrive at the Oval Office, shortly after we win the presidency… I will have the horrible war between Russia and Ukraine settled," Trump said on Saturday during a rally in Philadelphia.
During his speech, Trump also vowed to prevent World War III.
The US presidential election will be held on November 5. The main rivals in the race are US President Joe Biden, a Democrat, and his Republican predecessor, Donald Trump.
Earlier in the week, Trump said in an interview with the All-In podcast that it is understandable that Russia would be bothered by NATO troops on its border, adding that NATO's eastward expansion was a key reason for the Ukraine conflict. Trump vowed to not put US troops on the ground in Ukraine if he returns to the White House.