An M18 "Claymore" is an antipersonnel mine of United States origin. Antipersonnel mines are potentially very dangerous to non-combatants both during and long after the conflict, and as such, it is unlikely the US government would want American-made antipersonnel mines littered around Berlin, Singapore, Japan and Sidney as well as countless farms and forests, especially if done so by a trigger-happy paramilitary shadow organization.
When in use by the U.S. military, the M18A1 Claymore Anti-Personnel Mine is most often command-detonated. Such use is permitted by the Mine Ban Treaty. However, use of Claymore mines in uncontrolled (tripwire) mode is prohibited by the treaty.[5] Because of this uncontrolled mode, it is frequently listed in efforts to ban anti-personnel mines. While the United States has been an active participant in worldwide demining operations, and has signed the 1996 Protocol on Prohibitions or Restrictions on the Use of Mines, it has not signed the 1997 Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction, commonly known as the Ottawa Treaty. Under the 1996 Protocol on Prohibitions or Restrictions on the Use of Mines the U.S. forces may legally use the Claymore in victim initiated detonation as long as provisions of the protocol are met. Provisions of the protocol center around confining landmines to clearly known and marked areas such that the chances of civilian incursion into mined areas is so low as to minimize civilian risks and casualties. As such, it is a requirement for individual U.S. soldiers and Marines to know how to properly deploy and emplace the M18A1 landmine in compliance with appropriate regulations.
Because of what soldiers and military scholars poignantly refer to as 'political bullshit' it occasionally happens that one must use a blowtorch in place of a flamethrower. The Proximity Grenade is not a mine. It is a grenade. It says so in our arsenal records right here. It automatically disarms itself at the end of a battle thanks to a built-in timer. But just to be safe, we have a bright red light on the top that clearly marks the grenade. Notice how its a grenade, not a mine? Aliens don't know bright red means danger. People should. And just to be safe, we have a public awareness campaign in effect regarding the dangers of bright red lights on little metal softballs, but currently our budget can only afford 2-5 AM advertising slots.
In addition, that Barret .50 anti-material rifle that's not allowed to be used on people? Aliens aren't people. We're also aiming for their helmets, just to be safe. Notice how helmets are material? If we could communicate with the aliens we'd tell them we only want to shoot their helmets and they should take them off and leave them in a safe area, but wouldn't you know, we don't know their language.