FBU involvement in Africa

[Legbreaker]

I can see a ground burst nuke being the quickest and most effective way to block the canal. Perhaps one at each end just to be sure...
Sinking ships in the channel would work, but it's slow to do and could be prevented by effective naval patrols. And there's bound to be plenty of naval assets tasked with preventing it being blocked in any way (scuttled shipping, mines, etc). Logically, a nuke seems to be the best option.

The nuke probably wouldn't be targeted at the canal itself either - more effective to land/place it a hundred metres or so to the side and let the blast throw earth and rubble into the channel. Perhaps the Soviets could get a few local fanatics to do the job - drive a nuke in a van to the bank and hit the switch...