Many of us of a certain age remember the great film Red Dawn — the original, not the remake, which wasn't worth much. While there were plenty of technical issues, not least of which was a band of high school kids going up against Spetsnaz and wiping them out, it's still a great movie, a patriotic movie, and unlike anything you're liable to see in this day and age, it's an unabashedly pro-Second Amendment movie. It also was a late Cold War-era look at what could very possibly happen, should a major war break out in the United States itself.

The last major war we have fought was World War II, in which we were shielded by two vast oceans. And yet, Japanese troops landed in the Aleutians, Japanese submarines launched minor attacks on the West Coast, and German U-boats patrolled the American east coast within sight of city lights. 

Now an American Army general has a warning: We won't be so lucky the next time.

"If we're going against a pacing threat, power projection will be contested," Gen. Christopher LaNeve, the Army's acting chief of staff, told Fox News Digital on Wednesday.

He said the military is rethinking assumptions that were held during decades of fighting in Iraq and Afghanistan, when American forces could largely count on secure bases and supply lines at home.

"During the Global War on Terror, we took a lot of things for granted, because we could," LaNeve said during a small-group roundtable at the Association of the United States Army's annual conference in Washington this week.

There's an old saying that applies: We're always training to fight the last war. The wars in the Middle East were nasty, particularly the house-to-house urban combat in places like Fallujah. But we fought those wars with technical superiority; better equipment, better logistics, better medical support, even better food — not to mention uncontested control of the skies.

But a scrap with China? That's a whole different kettle of fish.

In a potential conflict with China, disrupting American military bases, transportation networks and communications could delay U.S. forces from reaching the battlefield. The Pentagon's latest report on China's military capabilities warns that Beijing has positioned cyber capabilities inside U.S. critical infrastructure networks that could be used to disrupt American military mobilization during a conflict.

The concerns come as the Pentagon places renewed emphasis on homeland defense and military installations as they prepare to potentially confront threats closer to home. U.S. officials have previously confirmed drone incursions over installations — including Joint Base Langley-Eustis in Virginia and Picatinny Arsenal in New Jersey. Though those incidents have not been publicly attributed to China.

"Publicy," being the operative term.

If there is to be another major war, and sooner or later, there will be, the United States simply won't have that 1945-level of protection by the Atlantic and the Pacific anymore. And keep this in mind: Thanks to the previous administration's utter disregard for border security and immigration laws, there are hundreds of thousands, perhaps millions, of people in the country right now who are from nations known to be unfriendly to the United States - including China and Iran.

So now, the nation's military training has to include this possibility. This is the nature of the threat, and it likely won't be Cuban paratroopers parachuting into the West to seize passes in the Rockies, only to run afoul of small-town American kids who grew up with a rifle in their hands. No, it will be preparatory actions by people infiltrated into the USA years, maybe decades earlier. It will be drone swarms. And, very likely, it will include the introduction of genetically engineered biological agents. 

And, it will happen here. 

Some might think this won't happen, that the cost to the attacker as well as the attacked will be far too high. But remember the nature of the enemy, especially Iran and Iran's terrorist minions, who don't care if they die as long as they strike first. And, of course, we must remember George Santayana's caution: Only the dead have seen the end of war.