The border between North and South Korea is closed after North Korea conducted its fourth nuclear test.
Read moreNorth Korea’s third nuclear test this month, which was a hydrogen bomb test, prompted the United Nations to impose sanctions on the country.
It said the nuclear test “poses a threat to international peace and security”.
But in response, North Korea’s leader, Kim Jong-un, ordered his country to resume operations at the border and called for all foreign media outlets to report on its progress.
“The DPRK is ready to continue its nuclear-powered missile and nuclear bomb tests, and to launch new and powerful nuclear and ballistic missiles,” Kim said in a speech on Thursday.
“If necessary, the DPRK will make another nuclear-tipped missile to hit its enemies, and the entire world will be forced to pay a heavy price,” he said.
The UN Security Council has been criticised by the North Korean regime for not responding sooner to North Korea and for not taking tougher measures to prevent a nuclear war.
The BBC’s Jim Muir in Seoul says North Korea has been doing more to build a nuclear arsenal in recent years.
What is a lolly?
Lolly is a type of dog or cat.
It’s a breed of small-to-medium sized dog that has a short, stout tail.
It can reach 20-25 centimetres.
The North Korean version has been called the dog of the mountains.
The dog has been used as a symbol of North Korea since it first became a country in the late 1950s.
In a sign of its increasing power, North Korean leader Kim Jong Un on Thursday announced a plan to build five nuclear reactors by 2020.
“To strengthen the power of the Kim dynasty, I have ordered that we will develop five nuclear power plants by 2020, and will use them as the nuclear weapons to strengthen the Kim family dynasty,” Kim Jong Il said during the address.
Kim said that he will personally lead the nuclear construction in the country’s three biggest cities, Pyongyang, Wonsan and Dandong.
The North Korean government has not yet released details of the reactors, but a nuclear expert told the AFP news agency that the reactors would be capable of producing up to 10 nuclear bombs.
North Korea has repeatedly said it is not interested in a diplomatic solution to its nuclear issues, but has agreed to restart stalled nuclear talks with the United States and China in return for food aid and economic aid.
Kim’s visit to Dandung, the capital of the North’s Sheungchang province, is seen as a show of strength.
He is scheduled to hold talks with Vice-Premier Hong Lei, a South Korean politician and former deputy defence minister, who was in charge of nuclear weapons during his father’s rule.
Meanwhile, the North is expected to announce that it has conducted its fifth nuclear test, according to South Korean media reports.
Pyongyang said it successfully tested an intercontinental ballistic missile on Saturday and that it successfully fired a satellite into space.
The missile flew about 1,500km (1,300 miles) and landed in the Sea of Japan.
North Korean leader Ri Yong-ho, who also heads the Workers’ Party, said in an address on Friday that North Korea was “reforming” its military and economy.