Hi. I would like to ask, is it honestly a good idea to take an enemy vehicle or wear the enemy’s armor and then return to your own people, at the risk of them attacking you before you are able to identify yourself?
Probably not, for exactly the reason you identified. Though, with the vehicle, sometimes the only available transport is still the only surviving option. So commandeering an enemy vehicle after combat may be necessary, though your characters would probably want to indicate that it had been captured, if at all possible, such as by defacing the iconography. They’d still probably want to be cautious approaching friendly checkpoints regardless, and “surrender” to their allies rather than risk taking a bullet.
As for taking enemy armor, things get more complicated and context matters.
You may come across conflicting information on if wearing an enemy uniform is a war crime (and, yes, if their armor is distinct to their faction, that’s a uniform.) This is both true, and untrue. Simply wearing an enemy uniform is not a war crime, what you do while wearing it can be, however. The same goes for their vehicles.
“Misusing” an enemy flag, insignia, or a flag of truce is the war crime. The hard part here is, “misusing,” (or “improper use”) is the legal threshold, and that is undefined.
A ruse de guerre, (literally: “ruse of war”) is legally accepted behavior. This can include wearing enemy uniforms for specific purposes, such espionage and sabotage. However, legally, while in disguise, a soldier cannot engage in combat operations. So, disguising yourself in enemy armor, and sneaking into a facility to assassinate someone, or to ambush unsuspecting troops is a war crime. While wearing their uniform to obtain intelligence, or to sabotage equipment is not. To be clear, ambushing enemy troops is an accepted ruse de guerre, you just can’t do it while wearing their uniform.
To be fair, I’m condensing a fairly complex legal concept. In general, international law tends to get very complicated, and when it comes to armed conflict, it gets extremely involved.
The good news is, wearing an enemy uniform because you’d otherwise be naked is entirely legal. At least internationally. Also, if the goal was to steal the transport and extract it, wearing their armor to get through checkpoints on the way out is legitimate. That’s fine. Sneaking in is fine too, so long as your unit switches back to their own uniforms before they start picking off potential enemies.
The title for the article, a false flag, was originally a nautical example of this behavior. A sailing vessel would fly a flag allied with their enemy to close to cannon range and open up with a broadside attack. Again, under modern law, if the ship swaps out it’s flag before opening fire, that’s legal, if it engages while baring the enemy’s flag, that’s a war crime.
There’s similar logic for crossing back over into friendly territory, with the added caveat that this is very dangerous. You soldiers would need to approach a friendly patrol or checkpoint while clearly surrendering. There’s some details here: It’s a war crime to execute a surrendering combatant, and that should buy your characters enough time to explain who they are. Now, keep in mind, they’ll be taken into custody, until their identities are confirmed. But, that doesn’t reflect on them in any real way.
Also, even though it’s a war crime, this is still a very dangerous situation. A jumpy recruit might accidentally shoot them. A soldier who doesn’t care may simply open fire before they can identify themselves. This is not a good situation to be in, but it’s automatically fatal, if everyone involved keeps their head and follows the law.
If their mission was to secure the vehicle, it’s probable they’d have some extraction protocol to ensure they weren’t staring down the barrel of a friendly fire incident. Probably a set location that was briefed that they’re arriving, and bringing the vehicle (or whatever the actual payload is) back. Of course, if things go wrong, they could end up stumbling into a friendly checkpoint as a last resort.
A detail here is, if they were trying to steal something, or extract a VIP, that vehicle, and the disguises are probably the best way to achieve their goals. Also, yeah, that is a legitimate ruse de guerre use of enemy gear.
Again, I am condensing a fairly complicated legal situation into a very clean line, while reality is far muddier. Also, in some situations, this may not matter. Guerrilla forces may not care about pesky things like war crimes, for example.
So, is it a good idea? Normally, no. However, sometimes it’s the most expedient option available.