President arrives at White House, removes mask and salutes

Marine One landed on the White House South Lawn at 6:53 p.m. Trump, again, did not stop and talk to reporters but made a dramatic return without speaking a word.

He, instead, walked up the steps of White House, faced the cameras and took off his mask -- in an apparent effort to project strength and flout public health protocols as he continues to battle COVID-19. Trump also gave a thumbs up and an extended salute to Marine One, before walking inside the residence. 

The president is returning to a White House plagued by COVID-19 as 18 people in Trump's orbit have reported testing positive since last week.

Multiple White House sources told ABC News there is "a full-blown freak-out" in the administration waiting to see who will be next to test positive -- with aides not trusting each other and some trying to find ways to avoid coming into work.

After spending three nights in the hospital, Trump is departing Walter Reed Military Medical Center in Bethesda, Maryland, en route to the White House, despite not having completed his full COVID-19 treatment.

Trump -- in a mask -- surrounded by Secret Service -- walked out of the hospital at 6:38 p.m. ET and waved to reporters as he entered a vehicle to take him to Marine One.

He did not answer shouted questions from the press on the health of his staff.

The president tweeted shortly before his departure that he "Will be back on the Campaign Trail soon!!!"

Earlier in the day, the president’s physician said he supported Trump's move to the White House but also acknowledged the president is “not necessarily out of the woods yet” and that he is on “uncharted territory” in terms of his treatment.

Guidelines from the Center for Disease Control and Prevention say that transporting a patient “outside of their room should be limited to medically essential purposes.”

Trump arrived on Friday evening after announcing at 12:54 a.m. on Twitter that he had tested positive for COVID-19.

After a request from Sen. Kamala Harris', D-Calif., team, there will be plexiglass between the candidates at Wednesday night's vice presidential debate, Frank Fahrenkopf, the chairman of the Commission on Presidential Debates told ABC News.  

Fahrenkopf also told ABC News that any guests who are not wearing a mask will be escorted out of the debate.  

"They've got to wear a mask, and if they take their mask off they're gonna be escorted out, and I don't care who they are, they'll be escorted out," Fahrenkopf said.

Vice President Mike Pence's communications director, Katie Miller, responded to the move with a statement that said, "If Sen. Harris wants to use a fortress around herself, have at it." 

Miller tested positive for COVID-19 in May.  

-ABC News' Averi Harper and Justin Gomez

The White House issued an updated public schedule that said President Trump would depart the Walter Reed "emergency landing zone" at 6:30 p.m. and arrive on the White House South Lawn at 6:40 p.m.