When White House budget chief Mick Mulvaney was asked why President Donald Trump had appointed former Marine officer John Kelly as chief of staff, Mulvaney had a simple explanation. “You know that he enjoys working with generals,” he said.

Donald Trump sits with National Security Advisor H.R. McMaster (3rd R) and Secretary of Defense James Mattis (R) at a meeting with European Union officials in Brussels , May 25, 2017. REUTERS/Jonathan Ernst

Within this rambunctious, idiosyncratic presidency, a small but growing group of former military leaders appear almost the only ones able to operate, survive and even thrive in the Trump administration. The president appears to be increasingly placing his trust in their discipline, loyalty and ability to influence and control those in his chain of command.

A triumvirate of America’s most respected generals – former Marine James Mattis as Secretary of Defense, serving Army Lieutenant General H.R. McMaster as national security advisor and former Homeland Security chief Kelly – now sit at the political heart of the administration. With Kelly running the day-to-day operations of the White House since replacing former Republican chairman Reince Preibus, their influence may increasingly reach well beyond foreign and security policy into national politics.

The hope of many in and outside government is that the commanders provide a much-needed dose of sanity and experience to an administration that badly needs both. Critics, however, accuse them of risking politicizing the armed services and lending credibility to a presidency that hasn't earned it.

The truth may be that the military officers are almost the only figures Trump trusts, respects or can be reliably expected to listen to.

America’s military leadership has, of course, been a fixture in the nation’s broader domestic politics since the days of George Washington and the Revolutionary War. World War Two commander Dwight D. Eisenhower and Civil War military supremo Ulysses S. Grant were the last two to make it to the Oval Office. Never in recent history, however, have there been quite so many armed forces figures swirling around the top echelons of power.

Other former top military leaders are also gaining important roles. Last week, former U.S. General Anthony Zinni was named as America’s envoy for resolving the diplomatic crisis around Qatar. It’s an appointment that has been broadly welcomed within the region and Washington policy environment, not least because so many civilian roles within the State and Defense departments remain unfilled.

Inevitably, some figures have become swiftly politicized. That’s particularly true for National Security Advisor McMaster – still a serving officer doing a role usually filled by a political appointee.

Last week, McMaster found himself on the receiving end of frenzied briefings from his newfound political enemies, many of them said to have originated from the circle of White House advisor Steve Bannon. McMaster is widely reported to have opposed Bannon on a number of issues including Russia sanctions, the Iran nuclear deal and troop numbers for Afghanistan.

Few doubt there are further political fights to come. That’s particularly true for Kelly, who must now run the entire White House political machine despite having relatively little experience of key areas such as dealing with Congress.

Trump has already lost one former general from within his administration – National Security Advisor Mike Flynn, a former chief of the Defense Intelligence Agency, over failing to disclose links to foreign governments. Flynn, however, was always one of America’s most controversial senior officers. Those who have followed have tended to be more conformist. Crucially, those who have remained have been much more likely to stick together.

Mattis, Kelly, McMaster and those still at the top of the U.S. military all served together in multiple Iraqi and Afghan campaigns. (In Iraq, Mattis was immediate superior to General Joseph Dunford, current Chairman of the Joint Chiefs and professional head of the U.S. military.)

This dynamic puts America’s serving senior officers in a sometimes awkward situation. Some have been more outspoken than others. Last week, a U.S. Coast Guard admiral was openly critical of the recently-announced ban on transgender troops, saying his priority was protecting his own transgender personnel. Others have avoided direct comments on the policy, which Trump tweeted out unexpectedly while Mattis was on leave.

Last week, U.S. Army Chief of Staff General Mark Milley told the National Press Club he knew nothing about Trump’s proposed ban on transgender troops until the tweet. Milley did add that it is not unusual for senior commanders to find out about presidential decisions from the media.

That appeared to be a veiled reference to the Bush and Obama administrations, both of which also gained a reputation for making public announcements on matters such as troop numbers for Afghanistan without pre-warning commanders in Washington and the field.

Under the Obama administration, those at the top of the military frequently complained the president was uncomfortable around his generals and largely avoided direct contact with them. Paradoxically, that administration was simultaneously accused of micromanaging missions, particularly involving Special Forces.

Trump, in contrast, has tended to let the generals run their own campaigns. He has granted the U.S. military much more latitude in conducting its operations and is reported to have given Mattis the authority to decide whether to send more U.S. troops into Afghanistan.

Some commentators worry that too little civilian scrutiny will be bad for the services. Reported civilian casualties from U.S. actions in Iraq, Syria and elsewhere have risen since Trump took office, leading to concerns the military is quietly shifting to the use of more indiscriminate force in those conflicts.

What may worry Trump more, however, is the perception that some of his top military trio may spend much of their time apologizing for him and America. With the hash tag“#presidentMattis” trending on Twitter last week, the president may also come to worry they have their own ambitions.

“Bear with us,” Mattis told a conference in Singapore in June, before paraphrasing wartime British Prime Minister Winston Churchill’s quotation that America would eventually do the right thing after exhausting other alternatives.

If America’s generals can take the credit for the Trump presidency not being a catastrophe, it’s at least possible one of them may yet make it to the White House themselves. If they can’t, however, they may find themselves taking an unfair portion of the blame for whatever the president does wrong.