President Donald Trump puts his hand to his ear as music plays during his arrival to speak to the national convention of the Veterans of Foreign Wars, Tuesday, July 24, 2018, in Kansas City, Mo. (AP Photo/Evan Vucci)
PHOTO: Evan Vucci/AP
President Donald Trump puts his hand to his ear as music plays during his arrival to speak to the national convention of the Veterans of Foreign Wars, Tuesday, July 24, 2018, in Kansas City, Mo. (AP Photo/Evan Vucci)
Now playing
03:39
Trump: What you're seeing is not what's happening
President Donald Trump signs the John McCain National Defense Authorization Act for the Fiscal Year 2019, during a signing ceremony Monday, Aug. 13, 2018, in Fort Drum, N.Y. (AP/Hans Pennink)
PHOTO: Hans Pennink/AP
President Donald Trump signs the John McCain National Defense Authorization Act for the Fiscal Year 2019, during a signing ceremony Monday, Aug. 13, 2018, in Fort Drum, N.Y. (AP/Hans Pennink)
Now playing
01:28
Trump: Rebuilding military like never before
John Kirby newsroom 02072018
PHOTO: CNN
John Kirby newsroom 02072018
Now playing
01:07
Kirby: Worried parade about Trump, not troops
(RtoL) US First Lady Melania Trump, US President Donald Trump, French President Emmanuel Macron and his wife Brigitte Macron, walk towards the US national flag held by soldiers, as a French joint-army brass band performs, at the end of the annual Bastille Day military parade on the Champs-Elysees avenue in Paris on July 14, 2017.  
The parade on Paris's Champs-Elysees will commemorate the centenary of the US entering WWI and will feature horses, helicopters, planes and troops. / AFP PHOTO / ALAIN JOCARD        (Photo credit should read ALAIN JOCARD/AFP/Getty Images)
PHOTO: ALAIN JOCARD/AFP/Getty Images
(RtoL) US First Lady Melania Trump, US President Donald Trump, French President Emmanuel Macron and his wife Brigitte Macron, walk towards the US national flag held by soldiers, as a French joint-army brass band performs, at the end of the annual Bastille Day military parade on the Champs-Elysees avenue in Paris on July 14, 2017. The parade on Paris's Champs-Elysees will commemorate the centenary of the US entering WWI and will feature horses, helicopters, planes and troops. / AFP PHOTO / ALAIN JOCARD (Photo credit should read ALAIN JOCARD/AFP/Getty Images)
Now playing
02:19
Trump tells Pentagon to plan military parade
BEIJING, CHINA - SEPTEMBER 03:  Chinese soldiers march past Tiananmen Square before a military parade on September 3, 2015 in Beijing, China. China is marking the 70th anniversary of the end of World War II and its role in defeating Japan with a new national holiday and a military parade in Beijing. (Photo by Kevin Frayer/Getty Images)
PHOTO: Kevin Frayer/Getty Images AsiaPac/Getty Images
BEIJING, CHINA - SEPTEMBER 03: Chinese soldiers march past Tiananmen Square before a military parade on September 3, 2015 in Beijing, China. China is marking the 70th anniversary of the end of World War II and its role in defeating Japan with a new national holiday and a military parade in Beijing. (Photo by Kevin Frayer/Getty Images)
Now playing
01:41
Here's how other countries do big events
Frederica Wilson John Kelly Trump call newday_00000000.jpg
Frederica Wilson John Kelly Trump call newday_00000000.jpg
Now playing
01:07
Wilson: I wasn't 'listening in' on Trump call
PHOTO: Alencar family photos
Now playing
03:53
Gold Star widow's full phone call with Trump
PHOTO: CNN
Now playing
01:28
Kelly: I first told Trump not to call families
michelle deford
PHOTO: CNN
michelle deford
Now playing
00:50
Mom: Someone else should make condolence calls
PHOTO: CNN
Now playing
02:06
Wilson: Trump didn't know slain soldier's name
trump calling families of niger kia troops sot_00005808.jpg
trump calling families of niger kia troops sot_00005808.jpg
Now playing
02:04
Trump: Obama didn't call slain troops' families
Gen Hayden
PHOTO: CNN
Gen Hayden
Now playing
00:53
Gen. Hayden: Trump threw predecessors under bus
Donald Trump John McCain war hero_00000911.jpg
Donald Trump John McCain war hero_00000911.jpg
Now playing
01:45
Donald Trump questions if McCain is a war hero
president trump afghanistan war plan troop address_00003227.jpg
PHOTO: CNN
president trump afghanistan war plan troop address_00003227.jpg
Now playing
01:34
Trump: We produce a special class of heroes
GREELEY, CO - OCTOBER 30:  Republican presidential nominee Donald Trump holds a rainbow flag given to him by supporter Max Nowak during a campaign rally at the Bank of Colorado Arena on the campus of University of Northern Colorado October 30, 2016 in Greeley, Colorado. With less than nine days until Americans go to the polls, Trump is campaigning in Nevada, New Mexico and Colorado.  (Photo by Chip Somodevilla/Getty Images)
PHOTO: Chip Somodevilla/Getty Images
GREELEY, CO - OCTOBER 30: Republican presidential nominee Donald Trump holds a rainbow flag given to him by supporter Max Nowak during a campaign rally at the Bank of Colorado Arena on the campus of University of Northern Colorado October 30, 2016 in Greeley, Colorado. With less than nine days until Americans go to the polls, Trump is campaigning in Nevada, New Mexico and Colorado. (Photo by Chip Somodevilla/Getty Images)
Now playing
01:19
Trump ignores query on transgender troops ban
GOP presidential candidate Donald Trump speaks to the crowd at a campaign rally January 27, 2016 in Gilbert, South Carolina.
PHOTO: Sean Rayford/Getty Images
GOP presidential candidate Donald Trump speaks to the crowd at a campaign rally January 27, 2016 in Gilbert, South Carolina.
Now playing
01:33
How Donald Trump talks about veterans

Editor’s Note: Barbara Starr is CNN’s Pentagon correspondent. The views expressed in this commentary are her own. View more opinion articles on CNN.

(CNN) —  

The 1.3 million members of the US military have one thing in common. Each one has taken an oath to defend the Constitution of the United States. They have sworn that they are willing to die in combat to defend the core values of this country. And that means they are willing to die on the battlefield for freedom of speech and freedom of the press.

Continuing to attack both of those fundamental American pillars is clearly something that President Donald Trump feels resonates with his political base, even after 19 months in office. But as the Commander in Chief continues uninterrupted in his attacks, there is a problem boiling to the surface. Defense Secretary James Mattis and Chairman of the Joint Chiefs General Joseph Dunford – two of the top commanders – are walking an increasingly fraught line, ordering troops to fight and die under a Commander in Chief who does not publicly share the values the troops are obligated to defend.

Trump is now an accelerant. At what was supposed to be a presidential speech to the Veterans of Foreign Wars this week, the President, as he almost always does, attacked the media, saying, “Don’t believe the crap you see from these people – the fake news.” Many in the audience cheered. And Dunford had just been there the day before. The VFW scolded its members on their reaction to Trump, saying it relies on the media to cover veteran’s issues.

But there had been a little noticed, more worrisome incident. In March, Trump appeared at the Marine Corps Air Station Miramar near San Diego. Speaking before hundreds of Marines, he again pointed to reporters covering the speech and called them “fake news,” leading hundreds of uniformed personnel to applaud wildly for a political statement attacking a press corps they are sworn to defend.

Military personnel are banned from political statements and activities. The United States military is the strongest in the world – not because of its billions of dollars in weapons – but because it serves the interests of the American people, instead of American political agendas. Senior Marine Corps leaders watched the Miramar event aghast, but did nothing.

Trump has now taken it a step further with what some say is an Orwellian declaration: “What you’re seeing and what you’re reading is not what’s happening.” But troops don’t have the luxury of serving only the parts of the nation’s fabric they agree with. They serve the nation. Despite Trump’s tendency to talk about the military as “his’” and “my generals,” nothing could be further from the truth. The US military is and must stay apolitical. It is not Trump’s.

So how long can Mattis and Dunford remain silent? Their own aides privately acknowledge both are in a tough position. They cannot contradict the President publicly. But outright politicization of the military is exactly what Dunford privately feared all the way back to the presidential campaign. He regularly declines to publicly answer any questions he feels touch too closely on Trump’s political agenda.

Mattis has gone further. He does not do interviews, and he has only appeared in front of the Pentagon briefing room cameras a handful of times. His own aides readily admit he becomes furious at stories or questions that appear to address any disagreements between him and the President, concerned a rift will sideline his influence with the President.

But many feel it’s all gone too far. Americans have a right to know the state of the US military. To keep a military low profile, Mattis had clamped down on releasing basic military information that has been publicly available for years. For example, the Pentagon no longer publishes a regular report on troop levels in Iraq, Syria or Afghanistan. Mattis believes it gives adversaries valuable information, even though there is no way of knowing how many are at any one location on a given day. Over time the Pentagon has provided what it describes as approximate numbers for Iraq, Syria and Afghanistan. Mattis has also forbidden detailed discussion of military “readiness,” whether the troops have all the training and equipment to fight.

However, as one military officer put it to me, “How much longer can he hide?” Mattis has not yet commented in detail on Trump’s Helsinki meeting with Vladimir Putin – even as he, as secretary, has taken a publicly hard line on Russia. He also has not commented on Trump’s latest threats against Iran, even as Iran has threatened to shut down Gulf oil shipping.

Get our free weekly newsletter

Everyone who knows Dunford and Mattis says they would never resign unless they are ordered to do something illegal, unethical or immoral – an unlikely scenario by all accounts. But the US military may be facing more significant dangers right now: Leaders who stay quiet, information that is not communicated to the public and young troops who don’t know they can only serve effectively by not engaging in fleeting political agendas.

When a casket of a returning fallen servicemember is met at Dover, nobody knows if they are a Republican or Democrat. What we know is they are American heroes. Senior leaders know they must keep that legacy alive for the generations who served before and those still to come. The challenge for today’s military leaders will be knowing when it is time to stand up and speak their minds in defense of the American values that the military has sworn to uphold.

Clarification: This article has been clarified to note that the Pentagon has provided approximate troop levels in Iraq, Syria and Afghanistan.