The move is an attempt to squeeze Pyongyang’s use of seagoing trade to feed its nuclear missile program.
“North Korea may now be only months away from the capability to strike the United States with nuclear-armed ballistic missiles,” U.S. envoy Robert Wood said.
The U.S. has the most powerful military in the world.
North Korea analysts said the next threat could come from underwater.
North Korea refused to give up its nuclear weapons.
North Korea is believed to have anywhere from 25 to 60 nuclear weapons.
News of Park’s alleged execution follows reports that North Korea’s second most powerful official after leader Kim Jong Un has been punished.
The South and North Development (SAND) research institute reported the situation in a village near the Punggye-ri nuclear facility.
Defectors claim that 80 percent of trees planted near the test site die, that underground wells have been evaporated and that babies in the region are born with birth defects at alarming rates.
The Punngye-ri underground facility hosted the country's sixth and most powerful nuclear test to date.
South Korean and Chinese scientists worry that a collapse at the mountain could trigger a radiation leak.
“We decided to release the manga after hearing from our residents that the current manual is hard to understand,” a Hokkaido official said.
Analysts say North Korea may have to move on to other tunnel testing sites or build new ones.
Pyongyang's deputy ambassador spoke to the U.N. General Assembly committee for disarmament, but skipped the most inflammatory parts of his statement.
The nuclear test has made the mountainous location unsuitable as a base.
New analysis uses North Korea’s estimated capabilities to calculate the amount of casualties that would result from a nuclear attack.
Russia's foreign minister said the U.S. only attacked Iraq after being "100 percent" sure it had no weapons of mass destruction and therefore wouldn't attack North Korea.
China has closed access to Mount Paektu after seismic shocks 10 minutes after blast.
The U.N. Security Council is expected to vote on a resolution imposing new restrictions on North Korea on Monday afternoon.