President Donald Trump on Monday defended his long-promised border wall a day after outgoing White House chief of staff John Kelly said plans for a solid concrete structure were ditched early on in the administration.

"An all concrete Wall was NEVER ABANDONED, as has been reported by the media," Trump tweeted. "Some areas will be all concrete but the experts at Border Patrol prefer a Wall that is see through (thereby making it possible to see what is happening on both sides). Makes sense to me!"

An all concrete Wall was NEVER ABANDONED, as has been reported by the media. Some areas will be all concrete but the experts at Border Patrol prefer a Wall that is see through (thereby making it possible to see what is happening on both sides). Makes sense to me! — Donald J. Trump (@realDonaldTrump) December 31, 2018

He later added, "I campaigned on Border Security, which you cannot have without a strong and powerful Wall."

Kelly, who will depart the administration on Wednesday, told The Los Angeles Times in an extensive interview published on Sunday that Trump's pledge to build a massive wall along the U.S.-Mexico is not referring to an actual wall.

"The president still says 'wall' — oftentimes frankly he’ll say 'barrier' or 'fencing,' now he’s tended toward steel slats," Kelly said. "But we left a solid concrete wall early on in the administration when we asked people what they needed and where they needed it."

Trump's Monday tweet comes amid a partial government shutdown that began Dec. 22 over his demand that Congress fund a $5 billion wall. He threatened to "close" the border if the money was not approved.

Congressional Democrats, who take control of the House of Representatives after returning to Washington on Jan. 3, have shown little interest in funding what incoming House Speaker Nancy Pelosi's deputy chief of staff called an "immoral, ineffective and expensive wall — the wall that he specifically promised that Mexico would pay for."

During his presidential campaign, Trump promised Mexico would foot the bill for his wall. He also insisted on precise terminology.

"It's not a fence," he said repeatedly before and after his election.

Jeb Bush just talked about my border proposal to build a "fence." It's not a fence, Jeb, it's a WALL, and there's a BIG difference! — Donald J. Trump (@realDonaldTrump) August 25, 2015

But earlier this month, amid government spending disagreements, Trump attempted to rebrand the wall as "artistically designed steel slats."

"The Democrats, are saying loud and clear that they do not want to build a Concrete Wall - but we are not building a Concrete Wall, we are building artistically designed steel slats, so that you can easily see through it," Trump tweeted on Dec. 18.

Days later, he tweeted a picture of a steel slat design, calling it "beautiful" and "totally effective."

A design of our Steel Slat Barrier which is totally effective while at the same time beautiful! pic.twitter.com/sGltXh0cu9 — Donald J. Trump (@realDonaldTrump) December 21, 2018

Sen. Lindsey Graham, R-S.C., who met privately with the president on Sunday, said Trump was in a "very good mood" and is open-minded about a compromise if it “achieves his goals of securing our border.”

Graham also reiterated Kelly's comment that the wall is not a concrete wall.

"The wall has become a metaphor for border security. And what we’re talking about is a physical barrier where it makes sense. In the past every Democrat has voted for these physical barriers," Graham said.

Trump on Monday also defended his decision to withdraw American troops from Syria while declaring victory over ISIS, which prompted the resignation of Defense Secretary Jim Mattis. He also blasted the "failed generals" who were "unable to do the job before I arrived" in an apparent jab to Mattis and other military leaders who have criticized his decision.

"If anybody but Donald Trump did what I did in Syria, which was an ISIS loaded mess when I became President, they would be a national hero," Trump said on Twitter.

If anybody but Donald Trump did what I did in Syria, which was an ISIS loaded mess when I became President, they would be a national hero. ISIS is mostly gone, we’re slowly sending our troops back home to be with their families, while at the same time fighting ISIS remnants...... — Donald J. Trump (@realDonaldTrump) December 31, 2018

"I campaigned on getting out of Syria and other places. Now when I start getting out the Fake News Media, or some failed Generals who were unable to do the job before I arrived, like to complain about me & my tactics, which are working. Just doing what I said I was going to do!" he added.

In an interview with ABC's "This Week" on Sunday, Retired Gen. Stanley McChrystal called Trump dishonest and answered affirmatively when asked if the president is immoral. He also said he does not believe that ISIS is defeated.

“I don’t believe ISIS is defeated. I think ISIS is as much an idea as it is a number of ISIS fighters," he said.

McChrystal worked as commander of U.S. forces in Afghanistan in the Obama administration but was forced to resign in 2010 after making critical comments about administration officials at the time in a magazine interview.

Graham told reporters Sunday after his private lunch with Trump that plans to withdraw 2,000 U.S. troops from Syria are "slowing down in a smart way."