President Donald Trump‘s health is being questioned after his cautious walk down the ramp at the graduation ceremony for the U.S. Military Academy at West Point went viral online.

A day before his 74 birthday, Trump appeared at the commencement ceremony at the United States Military Academy at West Point, which was originally postponed due to coronavirus pandemic and addressed the military cadets. After his speech, Trump carefully walked down the ramp, taking one step at a time.

Another video shows Trump struggling to hold a glass to take a sip of water. He is seen helping himself to move a glass to his mouth with the left hand.

After the videos of the incidents were posted on social media raising concerns about his health and age, Trump tweeted in his defense to the rumors, saying the ramp was “very long, “steep” and “very slippery.”

Trump is known to comment on the health of his rivals. In 2016, Trump’s campaign released a video ad, criticizing Hilary Clinton‘s “health and stamina” after she was videotaped stumbling when she got into a car after her 9/11 address at the World Trade Center in New York City.

“Hillary Clinton doesn’t have the fortitude, strength or stamina to lead in our world,” the ad said. “She failed as Secretary of State. Don’t let her fail us again.”

Trump also constantly attacks former Vice President Joe Biden with derogatory comments on his age and health.

In 2014, Trump also commented on former President Barack Obama‘s manner of getting off the plane, calling it “inelegant” and “unpresidential.”