"Joe Biden is humiliating our country on the world stage," Trump said on Tuesday. "He wandered off the G7 in Europe… he looked like he didn’t know where the hell he was, but he didn’t know where he was."
Trump also criticized an interaction between Biden and Pope Francis, as well as Biden’s behavior during a Juneteenth celebration and a campaign event alongside former President Barack Obama.
The White House has dismissed videos appearing to show Biden’s alleged cognitive decline as so-called "cheap fakes" that have been deceptively edited.
Biden, 81, is the oldest president in US history and would be 86 at the end of a potential second term in office.
Earlier this month, a Rasmussen Reports poll found that 57% of likely US voters believe Biden’s mental sharpness is in decline.
Last week, Trump campaign spokeswoman Karoline Leavitt said that US adversaries are plotting how to take advantage of Biden’s alleged cognitive decline.