An official from Seoul's defence ministry reportedly said the hermit country was building larger UAVs (unmanned aerial vehicles) with "greater range" and "the capability to be flown remotely by flight controllers."
Yonhap says test flights are underway and that the drones have been detected several times since the start of the year.
It adds that North Korean Chosun Central TV revealed a week ago that a new type of UAV was being developed.
No photos were provided, but the state-of-the-art drone is said to have tracking capabilities and the ability to carry out real-time observation.
In the past, North Korea has obtained technology from Russia and China to develop their UAV programme.
But another source at the Korea Defence and Security Forum said the country "clearly" seemed to be interested in building its own machine to replace the imported ones.
Christoph Bluth, a professor of International Relations and Security at Bradford University, told The Independent the reports were probably true, but added that the North Korean designs were unlikely to match the sophistication of Western drones.
"The US and South Korea have enhanced their radar capabilities to cope with UAVs. Drones can only effectively operate in an environment in which the party operating them has air superiority. This is not the case on the Korean peninsula," he added.
According to the Daily Mirror, government officials in South Korea have "asked scientists to create new electromagnetic pulse (EMP) devices to disable and bring the drones down."
An EMP is "a powerful burst of particles used to disable electronics and was used in the Star Wars: Clone Wars series as a method of killing fictional droids," the paper adds.
According to drone expert Joseph Bermudez, North Korea actually has "a longer history of using advanced drones than you might think".
"The country's interest goes back to the early 70s, when the US military flew drones along its coastline to gather intelligence," he says.
He adds that at least six North Korean drones have crashed in the South, with one found in an area with a nuclear power plant, "suggesting that the North was reconnoitering the plant for sabotage".
While "relatively unsophisticated", the technology has now reached the point where it could "present a security challenge for [South Korea] and US forces on the Korean peninsula", he continues.
"How rapidly that threat develops could depend on the North’s ability to acquire new technologies from China, Iran or elsewhere."
North Korea detonates 'biggest nuclear bomb yet'
9 September
North Korea has confirmed that it conducted a "nuclear warhead explosion" today, designed to counter "US hostility".
The announcement came shortly after a 5.3-magnitude earthquake was detected near North Korea's Punggye-ri nuclear site.
According to The Guardian, the magnitude of the earthquake indicates a device with a 20 to 30 kilotonne yield, "the largest yield estimate yet of a North Korean nuclear device".
The test is a "carefully timed gesture of international defiance, which will plunge east Asia into a new diplomatic crisis", raising fears in South Korea and across the world that the North is a step closer to having a useable atomic weapon, warns The Times.
Jeffrey Lewis, of the California-based Middlebury Institute of International Studies, says the seismic magnitude indicated that the test was "larger than the nuclear bomb dropped by the United States on the Japanese city of Hiroshima in World War Two".
Reactions from neighbouring countries have been swift, with many calling for emergency meetings to deal with the development.
South Korean President Park Geun-hye called the test an act of "maniacal recklessness" by North Korean leader Kim Jong-un, while the US warned of "serious consequences".
China's foreign ministry said in a statement that it "firmly opposes the test", while Japan's prime minister Shinzo Abe has called for an emergency meeting of the UN security council. "This is something we cannot tolerate," said the Japanese leader.
The test took place on the morning of North Korea's National Day, which celebrates the beginning of the current regime. "North Korea often uses such events as an opportunity for a show of military strength," notes the BBC.
North Korean builders 'given crystal meth' to speed up work
11 August 2016
North Korean developers are giving construction workers methamphetamine – crystal meth - to speed up production, according to local sources.
Hundreds of thousands of workers have been recruited to build a 70-storey high-rise apartment building and dozens of other structures in the capital Pyongyang.
"Project managers are now openly providing drugs to construction workers so that they will work faster," a source told Radio Free Asia. "[They] are undergoing terrible sufferings."
The broadcaster says the huge construction project is a "symbolic rebuke" of international sanctions imposed in response to North Korean leader Kim Jong-un's nuclear weapons testing.
People are reportedly working under harsh conditions late into the night and are being given the drug to keep them awake and active, as well as to suppress their appetites.
Human rights groups said the practice, if confirmed, would be a gross violation of rights and amount to slave labour.
"It's going to be hard to verify that this is happening, but if it is confirmed then we utterly condemn it," said Phil Robertson, the Asia director for Human Rights Watch.
An investigation by the Daily Beast last month revealed the extent of crystal meth production in the state and how it was being transported across the border to China.
"Within North Korea, there is an incredible proliferation of crystal meth. Defectors who have reached South Korea estimate up to 80 per cent of residents in some towns have used the drug," it said.
"More recently, the wives of North Korean Party cadre have apparently been trying out a drug diet, turning an ugly thing into a fad."
North Korea fires missile into Japanese waters
3 August
A ballistic missile launched by North Korea has landed in Japanese-controlled waters, US and South Korean authorities said.
The intermediate-range Rodong rocket was one of two test-fired by Pyongyang on Wednesday. It travelled a distance of 620 miles, landing in the Sea of Japan, while the other missile exploded shortly after launch.
The Japanese defence ministry said the missile had landed inside its exclusive economic zone, an area of ocean that covers 200 nautical miles over which Japan has jurisdiction.
Japan's Prime Minister, Shinzo Abe, said the action represented a "grave threat" and Tokyo would remain on alert in case of further launches, reports Reuters.
An official with the South Korean Defense Ministry told CNN that by firing a missile that capable of being equipped with a nuclear warhead, Pyongyang was openly showing its intention to "target our country, including our ports and airports, as well as our neighbours".
US Strategic Command issued a statement confirming it had detected what it believed to be the simultaneous launch of two intermediate-range ballistic missiles.
The US State Department condemned the action, which it said would "only increase the international community's resolve to counter" North Korea's actions.
The launch is the latest in a series by the isolated country in defiance of UN resolutions.
It has been conducting tests while openly voicing its discontent over a plan by the US and South Korea for an anti-missile defence system in the region.
North Korea state media endorses 'wise' Donald Trump
01 June
Donald Trump's willingness to abandon current US policy and open direct talks with North Korean leader Kim Jong-un might have won him an inconvenient ally. The presumptive Republican presidential nominee has been praised by a state-run website, which urges US voters to elect him over "dull" Hillary Clinton.
Writing an editorial in DPRK Today, Han Yong Mook dubbed the billionaire businessman "wise" – not a label he is used to receiving in his home country.
"Trump is not the rough-talking, screwy, ignorant candidate they say he is, but is actually a wise politician and a prescient presidential candidate," says Han, according to a translation provided by the South China Morning Post.
Han, who describes himself as a Chinese North Korea scholar, goes on to praise the businessman's willingness to enter direct talks with the pariah state. The editorial adds that negotiations rather than war will liberate the US people from "living every minute and second on pins and needles in fear of a nuclear strike".
The article also praised Trump's hint that he might withdraw troops from South Korea if Seoul does not contribute more money towards maintaining the US military presence in the country, which is still officially at war with its northern neighbour.
"Who knew that the slogan 'Yankee Go Home' would come true like this?" writes Han. "The day when the 'Yankee Go Home' slogan becomes real would be the day of Korean Unification."
Han was less kind to "that dull Hillary Clinton", rubbishing the former secretary of state's proposal to engage with North Korea using a similar approach to the one adopted for nuclear negotiations with Iran.
Aidan Foster-Carter, an expert on Korean affairs at the University of Leeds, told NK News the editorial was "very striking".
He added: "This is a timely reminder – if it were needed – of just how completely Trump plans to tear up established US policy in the region, and what an irresponsible, unthinking menace the man is."
What's like to be interrogated in the DPRK?
20 May
The veteran BBC reporter Rupert Wingfield-Hayes, one of several people to have recently been arrested and interrogated in North Korea, has given a harrowing account of his ordeal.
"I spent only 10 hours in detention," he writes. "But in that time I got to see just how easy it is for someone in North Korea to disappear."
What happened?
The BBC team were in North Korea's capital Pyongyang earlier this month to report on the visit of a delegation of Nobel prize-winners. The entire trip had been "exhausting and stressful," says Wingfield-Hayes. "We were all looking forward to a cold beer and a good night's sleep in Beijing."
But as they attempted to pass through immigration at Pyongyang airport, the journalist was held back by security officials, while his colleagues were allowed to proceed to the plane. "You will not be going to Beijing," a border guard told him.
"Now my sense of alarm was rising fast," says Wingfield-Hayes. He was taken to a conference room in a Pyongyang hotel where he was interrogated by a group of officials in "dark Mao suits".
What was the interrogation like?
"Mr Rupert," one of the officials said, "this meeting can be over quickly and simply, it will depend on your attitude." Wingfield-Hayes was accused of "insulting" the Korean people and presented with the offending stories that had been published online by the BBC.
"They began going through my articles word by word – finding offence in almost every one. But the words were not important; they were ammunition to throw at me, to force me to confess," he says.
The interrogators were relentless in their attempts. "Every two hours they took a break and another team stepped in," he says.
Meanwhile, his colleagues had raised the alarm and the BBC's Asia bureau editor Jo Floto, who was already in Pyongyang covering another story, was able to finally meet him more than five hours into his interrogation.
Wingfield-Hayes was then forced to sign a letter "apologising for the offence my articles had caused", while Floto vowed to ensure that "this kind of regrettable misunderstanding does not occur" again.
The BBC reporter was then released and allowed to return to his hotel, but it would be another two days before the team was finally allowed to leave the country.
Looking back on his experience, Wingfield-Hayes says it has given him a terrifying insight into North Korea's justice system.
"I got to feel the terror of being isolated and accused of crimes I had not committed, and to be threatened with a trial in which the evidence would have been irrelevant, and my guilt assured."
Who else has fallen foul of North Korean officials?
The BBC journalist's detention came less than two months after a US student who tried to steal a political banner from a Pyongyang hotel was sentenced to 15 years' hard labour.
Paraded in front of North Korean media, Otto Warmbier admitted committing "hostile acts" as he wept and begged for forgiveness. It is widely believed that he was coerced into making the confession.
Another American citizen, South Korean-born, Kim Dong-chul was also recently sentenced to ten years' hard labour for "spying".
Analysts say such detentions are a sign that leader Kim Jong-un and his government are trying to gain leverage over the US and other western nations.
"Washington has previously accused North Korea of taking Americans into custody as political pawns in its showdowns with the West over issues such as Pyongyang's nuclear weapons programme," said the Washington Post.
North Korea: BBC reporters expelled after 'displeasing' regime
9 May
A team of BBC reporters has been allowed to leave North Korea after being detained in Pyongyang for three days over accusations they had been "disrespectful" towards the country's regime.
Tokyo correspondent Rupert Wingfield-Hayes, producer Maria Byrne and cameraman Matthew Goddard were stopped as they prepared to leave the country on Friday after reporting on the visit of a delegation of Nobel prize-winners.
Stephen Evans, the BBC's Seoul correspondent who is currently in Pyongyang, told Radio 4's Today programme: "Just as they were about to board the flight, Rupert was held back. He was then taken to a hotel, a separate hotel to where we were, and interrogated for eight hours."
The corporation says the North Korean leadership had been "displeased with their reports highlighting aspects of life in the capital".
Under particular scrutiny was a broadcast aired last week in which Wingfield-Hayes suggested a visit to a hospital had been staged and that the patients and doctors were part of a "set-up".
He was also accused of being disrespectful to the nation's leader, Kim Jong-un, after saying he spent "a lot of time sitting in a large chair watching artillery firing at mountainsides".
The journalists were allowed to leave the country after Wingfield-Hayes signed what officials described as an "apology", although Evans called it a "confession", saying that their reporting was inaccurate.
O Ryong Il, the secretary general of North Korea's National Peace Committee, said the BBC team's coverage "spoke ill of the system and the leadership of the country" and that Wingfield-Hayes was now barred from entering North Korea.
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