The impoverished, isolated North insists that it needs nuclear and missile weapons for self-defence against "hostile forces", including the United States and its ally South Korea.
South Korea's military declined to comment.
It has conducted five nuclear tests since 2006 - three under Kim Jong-Un - and launched a number of missiles as it seeks to develop a weapon capable of reaching the U.S. mainland.
Fears Kim Jong-un is ready to launch a nuclear weapon are increasing as statements from the country have become more direct and aggressive following an announcement on Friday by US Secretary of State Rex Tillerson the period of diplomatic patience with the dictatorship is officially over.
North Korea's watchdog, 38 North, said the deeper the tunnel goes beneath Mount Mantap, the bigger the blast which can be contained there during testing.
UK House Prices Rise In March: Rightmove
But the March 2017 monthly rise has only been exceeded once at this time of year since 2007. The 1.3 per cent average asking price rise in the past four weeks is equivalent to £3,877.
North Korean State media said the country's latest rocket-engine tests were a "great leap forward", CNN reports, and Monday South Korean officials conceded Monday that the North's tests demonstrated "meaningful progress" in rocket-engine function. The Foreign Ministry of the DPRK (Democratic People's Republic of Korea) issued the warning, saying that North Korea would reduce enemy bases "to ashes" with nuclear warheads if its territorial sovereignty is breached.
The United Nations forbids North Korea from conducting long-range missile tests, but allows its satellite program for peaceful use. Trump said he had "meetings on North Korea", but did not specify with whom or what was discussed. "A missile has been launched".
"If they elevate the threat of their weapons program to a level that we believe requires action, then [the military] option's on the table".
The test site is close to where North Korea launched four extended-range Scud missiles into the Sea of Japan earlier this month. North Korean Ri Jong-chol, who was deported from Malaysia as there was insufficient evidence to charge him with Kim Jong-nam's murder, was likely an arms dealer, The Straits Times reported.
PHILIPPINES President Rodrigo Duterte said yesterday that he would not be intimidated by an impeachment complaint and threats of an global lawsuit for his anti-drug crackdown and added that he'd rather have criminals dead even in the "thousands or billions" if they threaten law enforcers than see his men killed. "It's important to them to have this ability to demonstrate technological prowess".