(CNN) In the moments before President Donald Trump was set to commemorate the 18th anniversary of the September 11 terror attacks , his mind was decidedly elsewhere.

"If it weren't for the never ending Fake News about me, and with all that I have done (more than any other President in the first 2 1/2 years!), I would be leading the "Partners" of the LameStream Media by 20 points. Sorry, but true!" he tweeted at 8:19 a.m. ET Wednesday after complaining about polling in Tuesday night's special election in North Carolina.

He followed up minutes later with a second tweet : "Leaving the White House soon to speak at the Pentagon. My great honor!"

Trump and the first lady marked the moment the first World Trade Center tower was hit -- 8:46 a.m. -- with a moment of silence on the White House South Lawn. The two solemnly bowed their heads as a bell rang.

Earlier in the day, Trump took to social media to describe the Federal Reserve as "Boneheads" and calling for an interest rate cut to "ZERO."

Trump has treated the anniversary with similar respect in the past.

In 2018, Trump spent the morning of 9/11 tweeting about text messages between Peter Strzok and Lisa Page and lamenting leadership at the Justice Department.

But in 2017, Trump tweeted only twice, and both times about 9/11.

Later Wednesday morning, Trump and the first lady attended commemorative ceremonies at the National 9/11 Pentagon Memorial. He laid a wreath, observed another moment of silence, and delivered remarks.

Trump recalled his personal memories of the terror attacks.

"I vividly remember when I first heard the news. I was sitting at home watching a major business television show," Trump said, noting that GE's Jack Welch was about to be interviewed "when all of a sudden they cut away."

Then, Trump claimed, he was looking out a window from his midtown office "when I saw a second plane go into the second tower."

Trump said he "knew the world had changed at that moment."

Trump has mentioned in previous interviews that he witnessed the second plane hit the second World Trade Center tower.

The anniversary of the terror attacks comes days after Trump scrapped a plan to meet with Taliban and Afghan leaders at Camp David, an effort to end America's longest war, after a Taliban car bomb killed a US soldier and 11 others last week.

Trump referenced the canceled talks during his remarks.

"They thought they would use this attack to show strength but actually what they showed is unrelenting weakness," he said, claiming that in the last four days, "We have hit our enemy harder than they have ever been hurt before and that will continue."

And, he warned: "If for any reason they come back to our country, we will go wherever they are and use power the likes of which the United States has never seen before."