During the 1990s, the U.S. Navy decided that it's future (in a post Cold War world) lay in "littoral (along the coast) warfare." This means that the navy has to face more trouble from it's least favorite weapon; mines. In the 1980s, the navy finally woke up to the growing threat of naval mines and began building mine warfare ships. Before that, the U.S. had been content to use mine sweeping equipment operated from helicopters. Against older types of mines, this was effective. But mine technology matched on, with many new mines that used technology that airborne minesweeping could not deal with. These more lethal and elusive mines had to be searched out and carefully destroyed. European nations began building "mine hunter" ships. These used more powerful sonar and robotic minisubs to go down plant the explosives to destroy these new mines that lay on the ocean floor in shallow water.
The U.S. built 26 mine hunters ships in the 1980s and 1990s. In the late 1990s a marine amphibious ships was converted to a mine warfare support ship. But, as usually happens to American mine clearing forces, naval commanders have a hard time taking naval mines seriously. Part of this comes from the fact that through most of the Cold War, the USN concentrated on high seas operations, away from any potential naval mines. Despite having two ships heavily damaged by Iraqi naval mines in 1991, the navy has a hard time taking the threat seriously. For example, 15 of the 26 mine warfare ships are manned by reservists and training exercises are not frequent, or realistic, enough to keep everyone ready for action. But there's another reason why mines never get the respect they deserve in the USN; the American fleet has never had a really disastrous encounter with naval mines. That may change some day in the not too distant future. Potential enemies have noted our attitude towards naval mines and seem prepared to take advantage of it.