"The assumption that nukes would primarily target ICBM silos seems suspect to me, as it would seem pointless to target silos which have already fired their miss

"The assumption that nukes would primarily target ICBM silos seems suspect to me, as it would seem pointless to target silos which have already fired their missiles." That's what SLBMs are for. An SLBM launched off the Oregon coast could hit missile silos in Montana in under 5 minutes. Launch in the middle of the night and there's not enough time to get the President out of bed and brief him before the missiles impact. (For that matter, if you park an SSBN 500 miles off Washington DC, it can get nuked in 3 minutes, probably killing the president as there's not enough time to get him down into the bunker. That's why the U.S. developed the SOSUS network, so you can't park an SSBN 500 miles off Washington without us knowing about it.) Modern SLBMs (1980s and onwards) are explicitly designed for this role, with depressed flight trajectories, low CEP, MIRVs, hardened silo penetrators, and warhead yields calibrated to destroy typical silos, given an accurate ground burst.