Trump's unsteady ramp walk raises health concerns. He blames 'very slippery' ramp

As US President Donald Trump turns 74 on Sunday, an incident a day earlier in which he appeared unsteady on his feet has revived concerns about his health.

Trump has always appeared vigorous for his age, but his sluggish walk on the ramp, balance problems and trouble enunciating certain words raised many an eyebrow as he heads into a gruelling re-election campaign.

Since Trump has regularly mocked the health and acuity of his presumptive election opponent, Democrat Joe Biden -- who is three years his senior -- the question of physical fitness could weigh heavily in the campaign ahead.

During the speech on Saturday, Trump used two hands to sip from a glass of water, and then gingerly descended a ramp as he looked at his feet and took what appeared to be 'baby steps'.

But Trump has defended himself.

"The ramp that I descended after my West Point Commencement speech was very long & steep, had no handrail and, most importantly, was very slippery," Trump said in a tweet.

"The last thing I was going to do is 'fall' for the Fake News to have fun with. Final ten feet I ran down to level ground. Momentum!"

Trump, however, did not address criticism that he drank his water using both hands.

It is not the first time that Trump has used two hands to sip from a cup of water, an odd tic that has led some to question whether he has a medical issue.

Trump's habit of sipping water with two hands has been noted since at least 2017.

Trump insists he is in perfect health and the White House recently released an annual physical that claimed he is in good shape for his age. He turns 74 on Sunday.