Washington (CNN) As President Donald Trump heads overseas for his first international trip as President, many in the international community will be watching his national security adviser, Gen. H.R. McMaster, who has just experienced one of the most politically challenging weeks of his career.

The trip -- to Saudi Arabia, Israel, the Vatican, a NATO summit in Brussels and a G7 summit in Sicily -- will be fraught with international risks, and much of it is riding on the ability of McMaster to steer the President in the right directions.

"It can be difficult to advise the President effectively given his seemingly short attention span and propensity to be easily distracted," a source knowledgeable about McMaster's day-to-day challenges told CNN.

The source added that McMaster's task -- being an honest broker of various national security options for the President -- is further complicated by fears on the National Security Council that Trump can be reckless with sensitive information.

"You can't say what not to say," the source said of Trump, "because that will then be one of the first things he'll say."

Some on the National Security Council see evidence of this dynamic -- and the price McMaster may have paid -- in the events of the last week, first reported by The Washington Post, after Trump discussed the ISIS laptop computer threat with Russian officials in a way that alarmed many in the national security and intelligence communities.

Sources who spoke to CNN would not go on the record due to the sensitive nature of the material being discussed. To a person, they expressed admiration for McMaster.

McMaster was asked to publicly step before the cameras Monday night and deny the story, Trump administration sources familiar with the matter told CNN, which demoralized some members of his own NSC.

National Security Council spokesman Michael Anton said that despite the impression some on the NSC have, McMaster was not pressured to defend the President.

"He had no hesitation," Anton told CNN. "He went out and he told the truth. He firmly believed The Washington Post story was inaccurate and the President had done nothing wrong."

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McMaster's statement that night, after which he took no questions, and his appearance in the press room the next day,upset some on his staff, multiple sources tell CNN. One knowledgeable source told CNN that there was a feeling among some on the NSC that the McMaster statements to the press were less than worthy of his reputation for honesty and candor and done solely to protect the President -- who then turned around and seemed to undermine on Twitter what McMaster had said in person to reporters.

In the end, this source feared McMaster hurt his own stature.

Others on the NSC disagree, telling CNN that McMaster was hampered by the classified nature of the subject he was discussing but that he remains firm in his belief that the President discussed nothing inappropriate. They see him as having maintained his integrity while defending the commander in chief.

"He doesn't want to be in the public eye but he didn't have a choice," the knowledgeable source said. "He tried to make the best of it."

No one, however, denies that McMaster has one of the most challenging jobs in the Trump White House.

Beyond dealing with Trump, sources tell CNN that McMaster is also forced to devote "too much of his time" to internal White House politics instead of national security matters, fending off challenges from White House strategist Stephen Bannon, senior adviser Jared Kushner and even the NSC chief of staff, retired Lt. Gen. Keith Kellogg, whom the source described as "directly attempting to undermine McMaster."

"McMaster knows that he's under attack from all sides in the building and even from departments and agencies," the source said. "It is ferocious."

Other knowledgeable sources describe an NSC staffed up by less-than-A-team individuals with allegiance to former national security adviser and retired Lt. Gen. Michael Flynn, who was fired in February, and an intelligence community populated by admirers of President Barack Obama's Director of National Intelligence James Clapper, compounding trust issues.

So why does a widely respected military mind continue in this job? The knowledgeable source described McMaster as a patriot with a sense of duty, one who is now living the lessons of his 1997 book " Dereliction of Duty: Lyndon Johnson, Robert McNamara, The Joint Chiefs of Staff, and the Lies that Led to Vietnam ," which faults military leaders for not sufficiently pushing back against disastrous political decisions made by President Lyndon Johnson.

"He's there to be the adult in the room," the source said, describing the national security adviser job as difficult when other voices, especially Bannon, challenge McMaster's sober policy recommendations with "emotions from the campaign. The President then doesn't know what to pursue."

The source said, "the last voice to speak to the President usually wins."

McMaster tells his staffers, "I'm not here to win an argument," the source said. "I'm here to provide information to the President."

McMaster increasingly finds himself in a situation where rivals in the White House "try to undermine him or leak information to the media that undermines the national security of the United States."

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Bannon is said to be "the biggest obstruction" to McMaster doing his job. In one recent situation, Secretary of Defense James Mattis, Secretary of State Rex Tillerson and McMaster had agreed that they would provide a range of options for the President in terms of how to proceed in Afghanistan, including a modest increase in the number of US troops in Afghanistan.

But before McMaster could make the recommendation, the option of a troop buildup was leaked to the media , with part of the leak including that Bannon opposed such a move . The blowback from conservatives and others caused the recommendations to be delayed, and others who supported the move to get "skittish." The leak was perceived within the NSC as Bannon or his allies trying to stamp McMaster's name onto the proposal and to push back against it through the media.

An NSC spokesman disputed that version of events to CNN, saying that the strategy was still under review as principals address certain concerns. "It had nothing to do with the leak," the spokesman said.

Morale on the National Security Council is said to have improved significantly since the dismissal of Flynn in February, with McMaster personally spending more time with NSC staff at the Eisenhower Executive Office Building, their work largely shielded from the day to day chaos of the FBI investigation and the President's tweets.

"He has a miraculous ability to leave behind the West Wing politics," the source said of McMaster. "He is an Army officer to the end."

Another bright spot, the source said, is that the NSC directorates are more emboldened to ignore controversial White House adviser Sebastian Gorka, whose security clearance is at an unclear status and whose views on national security matters are not taken seriously by many experts.

"Folks in the NSC have caught on and are talking to him less," the source said. "That's a good news story."

When it was suggested that that wasn't really much of a good news story, the source said, "well, that's where we are."