I have no problem making sure we have usable "tactical" nuclear weapons to make sure enemies with such weapons don't think they have a free pass to use them in the belief that we can only match a response with "strategic" weapons--that would justify the enemy's escalation to strategic nukes and so risk general nuclear war. Given that, we might be deterred from responding because of the risk of immediate escalation.
But this is a bad idea:
One of the proposed options, [Hans Kristensen, Director of the Nuclear Information Project, Federation of American Scientists] explained, might involve a first-of-its kind low-yield option wherein a different warhead would be configured onto existing nuclear armed Trident II D5 submarine launched nuclear missiles. Low-yield is as it sounds - smaller, more surgical and less destructive than most nuclear weapons.
"There are currently over 1,000 nuclear warheads in the US arsenal that have low-yield options. A yield is considered low if it’s 20 kilotons or less," an essay from the Federation of American Scientists states.
The Trident submarines is known to carry strategic weapons of higher yields. It is the most survivable portion of our nuclear triad (land-based ICBMs and long-range bombers are the other two legs).
It is a very bad idea to have an enemy detect a launch of a long-range missile from a known strategic nuclear weapon submarine, yet expect an enemy to wait and see what the detonation reveals about the yield.
An enemy will easily assume that a Trident submarine is launching a strategic weapon. And in the short flight time, may wonder if there are more of those missiles on the way but there is something wrong with their detection systems. Or maybe the enemy will think we've stealthed our missiles and the enemy is lucky they spotted one of the (flawed?) missiles.
Will the enemy then launch strategic missiles on this warning?
And are we really willing to expose the location of one of our few strategic missile submarines that are the heart of our nuclear deterrent to launch a single tactical nuke when we have other assets that could do the job?
What happens if the enemy then manages to attack the nuclear submarine? Will the crew in their stress of being under attack believe that the attack represents one aspect of an escalation to general nuclear war and so launch the remainder of their missiles? Their strategic missiles?
Keep tactical nuclear missiles away from our strategic ballistic missile submarines.
