The defense secretary offered unequivocal support to key U.S. ally South Korea.
Analysts say North Korea may have to move on to other tunnel testing sites or build new ones.
The U.N. Security Council is expected to vote on a resolution imposing new restrictions on North Korea on Monday afternoon.
Not even Pyongyang's sixth and largest nuclear test to date is shaking South Korea's president olive branch offer to Pyongyang.
North Korea's new tourism agency, run with help from the embassy, will offer Russians deals to visit "one of the safest countries in the world."
South Korea's President Moon Jae-In said the North was inching "closer to the threshold of the red line."
North Korean ruler Kim Jong Un examined plans targeting the U.S. territory but said he was not going to give the order to strike any time soon.
Kim Jong Un's 14-day absence from public appearances ahead of the celebrations may signal preparation for an at-sea SLBM test.
The U.S. announced the ban on its citizens traveling to North Korea in July and published it on the federal register on August 2.
A new sign erected on the 105-story Ryugyong Hotel's facade proclaimed the beginning of a new era for the country: "Rocket Power Nation."
An ejection test carried out on Sunday was the third of its kind in a month.
By the time the war ended, nearly 1.8 million Americans fought in the conflict, nearly 37,000 soldiers died and more than 7,800 remain unaccounted for to this day.
A month since the death of American tourist Otto Warmbier, who had suffered brain damage while under arrest in North Korea, the country shows the world what it has to offer, besides imprisonment.
It's President Moon's first formal overture to North Korea since taking office, and Beijing approves.
Diplomat David Straub told Yonhap News Agency this week that Pyongyang is raising its demands to free hostages.