Jura The idiot
General
... Mines may seem like an old, World War I technology...but they have been upgraded with all sorts of high tech capabilities, and they are still an effective and relatively cheap weapon that any large maritime oriented nation has to take into strong consideration when developing its order of battle.
I just googled this: a recent presentation about sea-mines getting even nastier than they are now ... and a mining operation can be performed quickly (for example, one B-1 "Lancer" can carry 24 two-thousand-pound mines!)