Veterans who have been in the service a while know that the exact dates and times of the biggest operations are typically classified until just before they pop off. But the troops have found ways of knowing what's coming because the command can't quite keep everything to "business as usual" while also preparing for a big push.

Here are six signs that sh*t's about to get real:

1. The commander shows up to inspections

Lt. Col. Matthew Danner inspects a rifle aboard the Wasp-class amphibious assault ship USS Essex, July 31, 2018.

In theory, the commander cares about all inspections, but he or she typically leaves the actual inspecting to their noncommissioned officers and platoon leaders. After all, company commanders and above have a lot to keep track of.

But sometimes, the first sergeant and commander are involved in more inspections than normal, and are checking for more details than normal. It's a sign that they're worried weapons, vehicles, and troops will see combat soon, making an untreated rash or rust damage much more dangerous.

2. Low-level, constant exercises or operations suddenly stop

Soldiers training at the National Training Center at Fort Irwin, California, undergo a CS gas attack.

When a force is built up for a potentially big fight, the commanders have to keep everyone razor sharp and focused. If the troops aren't in regular combat, this is typically accomplished via small exercises and large drills.

But, if the fight is about to start, the higher-ups want to ensure that everyone gets a little rest before going into the big battle. So, leaders get word from their own bosses to cease unnecessary training and operations the days immediately preceding the fight, and troops may even get official confirmation 24 hours out along with orders to rest up.

3. All the headquarters pukes are suddenly mum, or are talking in whispers in corners

But of course, not every low-level soldier can be kept out of the loop. Someone has to look at where the moon will be on different nights, cloud cover, whether the locals will be outside or in their homes during normal patterns of life. Someone has to move the right equipment to the right spots, and someone runs the messages between all the majors making the plans.

So, those people are all low-ranking, yes, but they're also in the know. They'll respond in one of a few ways, usually spilling the beans to close friends or cutting themselves off from everyone — which are dead giveaways in their own right. If the intel guy who typically wants to talk to everyone is suddenly mum or will only talk in whispers to close friends, get ready for a fight.

4. A whole bunch of fresh supplies arrive

Marines deliver an M777 howitzer via MV-22 Osprey slingload during training in Australia in 2018.

Here's a little secret: For as much as all the troops complain about always having to deal with old, hand-me-down gear, the U.S. is actually one of the best-supplied militaries in the world, if not the best supplied (we're certainly the most expensive). But all of those supplies are typically sent to top-tier units or units about to go into the fight.

So, if you're not in a Special Forces unit but the supply guy shows up with a ton of useful, new gear — especially batteries —that your unit has been asking for — and failing to receive — then you might be going into combat. Get to know the equipment quick.

5. A sudden, seemingly unprompted, nice meal

Pizza Hut shows up at the Marines' base just before the invasion of Iraq begins in "Generation Kill." (HBO)

As odd as it sounds, an unexpected nice meal is a dead giveaway that troops are about to experience something rough. If you're a soldier in the middle of a huge force, it's a good bet that the "something rough" is the planned operation.

This sometimes comes up in movies and TV, like in "Generation Kill," when 20 cars showed up at the wire filled with Pizza Hut while the Marines were waiting for the invasion of Iraq to begin. Driver and comedian Ray Person immediately calls it,

"Sh*t is on. Has to be."

6. Comms blackout

Marines communicate with family and friends on new morale internet lines in 2011 in Kabul, Afghanistan.

Of course, the officers typically want to tell all their troops what's going on and get them mentally prepared for the fight, but there's a big step they need to take to make sure word doesn't leak out: a communications blackout. Internet and phone access to the outside world is cutoff so no one can send an errant text home and let the enemy know the invasion is coming.

So, if the morale lines suddenly cut off, go ahead and report to your platoon, because word is coming down that something has happened or is about to.

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