More than 60 percent of U.S. submarine-based reconnaissance activities are focused on Pacific areas including the Korean Peninsula, according to a recent report by two American nuclear experts.

According to the report on U.S. nuclear forces by American scientists Hans Kristensen and Robert Norris, Washington has deployed 14 Ohio-class nuclear-powered submarines, equipped with Trident II D5 ballistic missiles, to the Pacific and Atlantic operational areas for nuclear deterrence.

Observers say the U.S.’ strengthened operations in the Pacific indicate its growing concerns about nuclear capabilities of its potential adversaries such as China and North Korea.