Some are calling it the "latte salute."

When President Obama stepped off Marine One at the Wall Street landing zone in New York City, en route the United Nations, he saluted two Marines at the bottom of the stairs as he held a coffee cup in the same hand.

The unusual gesture appeared in an Instagram video posted by the White House on social media. Obama is also wearing sunglasses as he arrived, with the first lady not far behind.

The video drew ridicule from some Instagram users, who saw the unorthodox salute as "un-presidential."

"Hopefully it was just a slip by this President," one user posted.

Others saw unnecessary nitpicking in the criticism.

"People are dying from disease, abuse or even hunger," another user commented on the video. "Priorities."

While it is protocol for U.S. service members in uniform to salute the commander in chief, it's not required for a civilian president to salute back, military experts say. Ronald Reagan is thought to have set precedent for the practice back in 1981.

However one feels about today's salute, it's unlikely any coffee was at play. President Obama prefers hot tea.