Donald Trump's rhetoric about 9/11 has always been ... how do I put this gently ... problematic. The day of the attacks, for example, the future president seemed principally focused on how the destruction of the Twin Towers affected his ability to boast about the height of one of his nearby properties.

As a candidate in 2016, Trump frequently referenced the 9/11 attacks, though as the Washington Post reported at the time, "[S]everal of Trump's statements about what he witnessed that day appear to be greatly exaggerated or false."

That includes an incident in which the New York Republican claimed he helped clear rubble and search for survivors in the aftermath of the terrorism, and another incident in which he falsely said he watched people jump from the World Trade Center.

As a rule, lying about 9/11 is the sort of thing that can cause trouble for a politician, though Trump ended up winning anyway.

All of this became relevant anew this morning, when Trump hosted a signing ceremony for a bill on the 9/11 Victim Compensation Fund, which recently passed the House and Senate, despite modest and inconsequential Republican opposition. The president was never especially invested in the fate of the legislation, but he did agree to sign it, which is great news for the affected first responders and their families.

But at today's White House event, Trump added a line that stood out:

"In a few moments, I will sign the 9/11 Victims Compensation Fund. This law makes permanent the financial support for families who lost precious loved ones as a result of September 11th attacks. It also provides pensions for those who are suffering from cancer and other illnesses stemming from the toxic debris they were exposed to in the aftermath of the attacks. Many of those affected were firefighters, police officers, and other first responders. "And I was down there also, but I'm not considering myself a first responder. But I was down there. I spent a lot of time down there with you."

There are just a couple of problems with this.

The first is that it may not be true that Trump was "down there" on 9/11, spending "a lot of time" with first responders. As Vox's Aaron Rupar noted, there's simply no evidence to support the president's assertions.

Snopes investigated Trump's 2016 claim by speaking to officials from the New York City Fire Department (FDNY) and construction demolitions experts who were at Ground Zero in the hours and days after the 9/11 attacks. Nobody could recall even seeing Trump at the site. Snopes also details how Trump has a history of exaggerating the role his company played in the recovery efforts.

But let's go out of our way to be generous and give Trump the benefit of the doubt. Let's say for the sake of conversation that he really did spend "a lot of time" with first responders, "down there" at Ground Zero in the immediate aftermath of the attack. Let's also say there's literally no proof to substantiate any of this because Trump, shy and unassuming, made a point to obscure his efforts and keep a low profile.

Even if we make those assumptions, we're left with a different question: why exactly did Trump think it was a good idea this morning to make the bill signing about him?

Look again at the context: the president referenced grieving families and ailing first responders, who'll benefit from the new law. But it was the next moment when Trump said, "And I was down there also."

That's probably a lie, but even if he was there, what possessed him to tie today's bill signing back to himself?

Trump has proven himself to be bad at governing, but we're occasionally reminded that he struggles with the ceremonial aspects of his job, too.