Trump headed to visit a 9/11 memorial site in Pennsylvania. Photo: Evan Vucci/AP/REX/Shutterstock

Tuesday marks the 17th anniversary of the September 11 terrorist attacks, during which approximately 3,000 people were killed after airplanes flew into the World Trade Center, the Pentagon, and a field in Shanksville, Pennsylvania. And to the surprise of absolutely no one, President Donald Trump sure seems to be having a tough time appropriately honoring the occasion.

Trump started out the somber day in his usual fashion: tweeting about Hillary Clinton and special counsel Robert Muller’s investigation into Russian interference in the 2016 election. Of course.

“We have found nothing to show collusion between President Trump & Russia, absolutely zero, but every day we get more documentation showing collusion between the FBI & DOJ, the Hillary campaign, foreign spies & Russians, incredible.” @SaraCarterDC @LouDobbs — Donald J. Trump (@realDonaldTrump) September 11, 2018

The president then briefly went back and forth between tweeting about “#September11th” and live tweeting the rest of Lou Dobbs’s Fox News program, before posting about his attorney Rudy Giuliani, whom he once reportedly referred to as a little baby who needs his diaper changed:

Rudy Giuliani did a GREAT job as Mayor of NYC during the period of September 11th. His leadership, bravery and skill must never be forgotten. Rudy is a TRUE WARRIOR! — Donald J. Trump (@realDonaldTrump) September 11, 2018

Trump, of course, then continued to tweet — and excitedly reminded us just how long it’s been since the attack:

17 years since September 11th! — Donald J. Trump (@realDonaldTrump) September 11, 2018

Shortly after, Trump and his wife, First Lady Melania Trump, arrived at an airport in Johnstown, Pennsylvania. They were en route to visit the Shanksville memorial site of United Flight 93. But upon arrival, the president had a rather … odd … reaction: he was photographed emphatically pumping both of his fists.

.@realDonaldTrump First Lady Melania Trump greet supporters as they arrive in Johnstown, PA to attend the Flight 93 September 11 Memorial Service in Shanksville, PA pic.twitter.com/SRMBvlDLKJ — Doug Mills (@dougmillsnyt) September 11, 2018

Immediately after the fist pump, Trump and the First Lady appeared to be having a great time greeting supporters at the airport.

Donald Trump and supporters on 9/11. Photo: Evan Vucci/AP/REX/Shutterstock

Later, when it was time for Trump to give a speech at the Shanksville memorial site, the president walked up to the podium — while pointing at people in the crowd and mouthing the words “thank you” as they clapped for him. That moment occurs around the 56:50 mark in the longer video here, but a shorter clip of his speech, during which he slowly read aloud from a teleprompter, is below.

"On September 11, 2001, a band of brave patriots turned the tide on our Nation's enemies and joined the immortal ranks of American heroes." — President @realDonaldTrump at the Flight 93 September 11 Memorial Service pic.twitter.com/uP6rcSnyUj — The White House (@WhiteHouse) September 11, 2018

The president and first lady also walked around the Flight 93 National Memorial with the park’s superintendent. Naturally, Trump couldn’t resist giving photographers a big thumbs up as he enjoyed himself on the tour.

Trump giving a thumbs up at a 9/11 memorial. Photo: Kevin Lamarque/REUTERS

Then it was back to Twitter, so he could share a Breitbart link about “small business optimism.”

We will continue to update this post throughout the day as Trump attempts to mourn a national tragedy.

This post has been updated.