(CNN) Defense Secretary James Mattis begins his second year in the Trump Administration with perhaps just one absolutely crucial task -- stopping President Donald Trump from going to war against North Korea.

Along with Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, Mattis will spend the next few weeks walking a fine line. The two must assure the President that there are credible US military options to stop North Korea if it comes to war and they launch a missile at the US or an ally, while at the same time continuing to make clear what a disaster a war would be.

How both men navigate this political minefield in the second year of the Trump White House may move them far outside the cocoon-like zone they operated in during the first year of the administration when they kept largely out of the public eye.

The urgency of the situation is growing in some quarters of the administration as concern about Kim Jong Un increases. Look no further than a recent statement by CIA Director Mike Pompeo who told a Washington audience last week that "North Korea is ever closer to being able to hold America at risk." The CIA has concluded that North Korea could be just a "handful of months" away from being able to put a nuclear warhead atop a missile that could hit the US.

That assessment may well be the reason that in December, national security adviser HR McMaster said the potential for war with North Korea is "increasing every day."

Nobody claims North Korea is likely to attack. But if Kim simply tells the world he's got that capability, what does the US do? What if he test fires a missile with a warhead even into the ocean? What if he conducts some type of atmospheric test? Could any president of the United States allow that to happen?

There is one major caveat. If sanctions pressure Kim so much that he cannot afford to continue his weapons development efforts, that could push off any US decision for months. Right now, the Pentagon is not betting on it. Mattis, in a joint appearance with the South Korean defense minister last week, said North Korea is "a threat to the entire world."

For the last year, it's been no secret that Mattis and Dunford have taken pains to control their public appearances. Both men feel a relatively low profile with limited exposure to the media will not only keep them in Trump's good graces, more importantly it will preserve their influence with him.

However, critics privately suggest working for "an audience of one" who always wants to be in the headlines means not interacting with the American people as much as some of their predecessors have.

Both men are always careful to defer to Secretary of State Rex Tillerson's efforts to press for diplomatic pressure on North Korea through sanctions. But there may now be cracks in that carefully constructed effort.

The Commandant of the Marine Corps Gen. Robert Neller apparently feels no such political pressure to keep from speaking his mind. Last week he warned America, and its Marines, that war with an enemy like North Korea "will be a very, very kinetic, physical, violent fight over some really, really tough ground and everybody is going to have to be mentally prepared."

Neller did not directly address recent tweets by both Trump and Kim about their respective "buttons" that they could push to launch military attacks, but he did say that war with North Korea would be a "different sort of fight" that wouldn't just involve "a bunch of things flying around."

Neller's remarks may in fact signal the beginning of a more public conversation that Mattis and Dunford may not be able to avoid, not just about North Korea but also a myriad of issues they have not been talking about much.

Both men are scheduled for extensive congressional testimony on the upcoming defense budget. They will have to defend more than $500 billion in spending for new ships, aircraft, and weapons. A nuclear review scheduled to be published this week is expected to call for development of low yield nuclear bombs -- a move likely to infuriate China, Russia and Kim. Trump's new emphasis on being ready to counter Russia and China will also draw attention.

One concern, is this may distract from the "war on terror." In just the last week in Kabul, three devastating attacks against a local base, a hospital and a hotel have called into question the ability of the Afghan government to secure its people after 16 years of US support. Nearly $1 trillion in spending, nearly 2,000 Americans dead and over 20,000 wounded and the Taliban still has influence over 40% of the population -- 13 million people.

In addition, an obscure border war between Turkey and Syria is threatening to catch US troops in their crosshairs and open up a new safe haven for ISIS.

The risk of Pentagon leaders not continuously talking to the American people becomes even more critical when there is a crisis.

The October ambush of a Green Beret led team in Niger in October and killing of four US troops sparked intense debate about the role of US special operations forces in the war against ISIS and al Qaeda. They are risking their lives not just in Iraq, Syria and Afghanistan, but also in Yemen, Libya, Somalia and other remote areas. The Niger mission remains classified pending an investigation. But the questions arising from what went wrong on that mission and others are not going away in year two of the Trump administration.

When the President stands before Congress and touts success in America's war and that we have the strongest military ever, he may be right. But then again, without more discussion and transparency, how would we know?