WASHINGTON — For most of this year, Pentagon planners have been developing a new joint war-fighting concept, a document meant to guide how the Defense Department fights in the coming decades.

Now, with an end-of-year deadline fast approaching, two top department officials believe the concept is coalescing around a key idea — one that requires tossing decades of traditional thinking out the window.

“What I’ve noticed is that, as opposed to everything I’ve done my entire career, the biggest difference is that in the future there will be no lines on the battlefield,” Gen. John Hyten, vice chairman of the Joint Chiefs of Staff, said during an Aug. 12 event hosted by the Hudson Institute.

The current structure, Hyten said, is all about dividing areas of operations. “Wherever we go, if we have to fight, we established the forward edge of the battle area, we’ve established the fire support coordination line, the forward line of troops, and we say: ‘OK, Army can operate here. Air Force can operate here,’ ” Hyten explained.

“Everything is about lines” now, he added. But to function in modern contested environments, “those lines are eliminated.”

What does that mean in practice? Effectively, Hyten — who will be a keynote speaker at September’s Defense News Conference — laid out a vision in which every force can both defend itself and have a deep-strike capability to hold an enemy at bay, built around a unified command-and-control system.

“A naval force can defend itself or strike deep. An air force can defend itself or strike deep. The Marines can defend itself or strike deep,” he said. “Everybody.”

That “everybody” includes international partners, Hyten added, as the U.S. operates so often in a coalition framework that this plan only works if it can integrate others. And for the entire structure to succeed, the Pentagon needs to create the Joint All-Domain Command and Control capability currently under development.

“So that’s the path we’ve been going down for a while. And it’s starting to actually mature and come to fruition now,” Hyten said.

The day before Hyten’s appearance, Victorino Mercado, assistant secretary of defense for strategy, plans and capabilities, talked with a small group of reporters, during which he noted: “We had disparate services [with] their concepts of fighting. We never really had a manner to pull all the services together to fight as a coherent unit.”

Mercado also said the war-fighting concept will directly “drive some of our investments” in the future and tie together a number of ongoing efforts within the department — including the individual combatant command reviews and the Navy’s shipbuilding plan.

“I can tell you there’s some critical components [from those reviews] — how you command and control the forces, how you do logistics; there are some common themes in there in a joint war-fighting concept,” he said. “I can tell you if we had that concept right now, we could use that concept right now to influence the ships that we are building, the amount of ships that we need, what we want the [combatant commands] to do.

“So this war-fighting concept is filling a gap. I wish we had it now. Leadership wishes we had it now,” he added. “It would inform all of the decisions that we make today because now is about positioning ourselves in the future for success.”

Like Hyten, Mercado expressed confidence that the concept will be ready to go by the end of the year, a deadline set by Defense Secretary Mark Esper. But asked whether the department will make details of the concept public when it is finished, Mercado said there is a “tension” between informing the public and key stakeholders and not giving an edge to Russia and China.

“I think there is an aspect that we need to share of this joint war-fighting concept,” he said. “We have to preserve the classified nature of it. And I think I have to be careful what I say here, to a degree.”