How worried should we be about present tensions?
"We have had a few episodes like this in the past, but luckily they have been few and far between. It's too early to talk of 'consequences'.
"In the worst case, Koreans on both sides of the 38th parallel will suffer incalculable disaster. A somewhat more likely course is that, at some point in the next few weeks, the fever will break, people and governments will realise they are all too close to the edge of the precipice for no good reason, tones will be softened, voices lowered. Everyone will declare victory and get back to what is important – figuring out how to re-establish structures and habits of interaction between the parties that will provide a measure of stability and a modicum of space in which diplomacy can function and, who knows, maybe even make progress."
Visiting scholar, Center for International Security and Cooperation, Stanford University
What domestic factors are playing a role in North Korea's bellicose stance?
"The consolidation of Kim Jong-un's position as the new leader is a major factor in the recent escalation of threats directed at the US and its allies. This is an opportunity for mass demonstrations against US imperialism and other activities to shore up loyalty to the regime.
"A state of emergency also conveniently deflects the attention of the population from other grave challenges, such as the food and energy shortages. However, during the current phase of the crisis the real audience for Pyongyang's statements is the US and South Korea."
Research fellow, Institute for Security and Development Policy, Beijing, China
To what extent might the military be influencing (or forcing) Kim Jong-un's hand?
"As for 'force', I'd be very doubtful. The system has not functioned for 60 years in anything but a top dog mode, and if anyone steps over the line or seems to threaten the supreme ruling position of the leader, they are despatched without any fuss.
"Unless the system has gone completely off the rails, Kim Jong-un is in charge, even though he is still a young man, still dependent on his advisers, still sorting through the process of finding out who he can trust, and who he can't."
"Contrary to speculation at the time of Kim Jong-il's death that North Korea would be ruled by a committee of senior officials with Kim Jong-un as a figurehead, it appears that Kim Jong-un has genuinely assumed his father's position as supreme leader. So while he is presumably being briefed and advised by the generals, ultimately Kim Jong-un himself is calling the shots.
"The purge last year of Ri Yong-ho, who was one of the most senior military officers in North Korea, demonstrated Kim Jong-un's control of the military. The person who is thought to have most influence on Kim Jong-un is his uncle, Jang Song-thaek, whose background is in the party, not the military."
What is the humanitarian situation in North Korea?
"What is clear is that since Kim Jong-un we have seen a serious crackdown on the border of North Korea and China, with increased efforts by both governments to prevent North Koreans from fleeing the county and, if they are caught in China, sending them back into the hands of North Korea's security services where they face beatings, interrogations and worse.
"North Koreans we've interviewed outside the country say that the situation is getting worse in terms of basic survival and rights abuses, so I assume that some of what we are seeing is an effort to divert people's attention to an external threat and away from the government's depredations against its own people."
Deputy director, Human Rights Watch, Asia Division, Bangkok, Thailand
Are North Koreans suffering acute food shortages?
"Although there is a lot of talk about North Korea as an international beggar with its hand constantly outstretched for handouts, in recent years that actually has not been the case. The amount of food aid appears to have dropped significantly (though one has to be careful here because the Chinese contribution remains unknown). Overall, the North Koreans have become adept at doing more with less, or scraping by on practically nothing.
"It is interesting to note that one of the problems is the price of grain – which the government does not control. The public distribution system – rations – fell apart years ago and is only a patchwork now. So, many people have to purchase their food on the market – just like the rest of us. When you see reports of 'reduced rations', you have to bear in mind that the ration system is no longer the only way, and in most cases not even the primary way people get their food.
"Yet who controls the price of food? Rich merchants, speculators, corrupt officials. Purists would say the price is set by 'market forces', which as we know from experience with our own economies these days can leave a trail of hardship if left completely on their own.
"North Korea continues to face regular, significant food shortages. The UN World Food Programme (WFP) has been providing food assistance in North Korea since 1995, saving lives and making significant inroads into levels of child malnutrition. WFP's current operation targets up to 2.4 million children and mothers in 85 counties across North Korea.
"An emergency operation was launched [in 2010] to address sudden increased needs following one of the most bitter winters in living memory, and a squeeze on commercial imports and bilateral food assistance."
Asia spokesman, UN World Food Programme, Regional Bureau for Asia, Bangkok, Thailand
How much does North Korea rely on outside aid and where does this come from?
"North Korea has long been unable to meet its own food and energy needs, and is forced to rely on outside aid (a shortfall in rice production of 100,000 tonnes last year was made up by outside donors). In the past, the majority of aid came from the US and South Korea (the US provided $1.3bn of assistance between 1995 and 2008), but aid from both countries has been largely cut off since 2009.
"The European Union continues to provide North Korea with some food aid (most recently €10m in emergency aid during the food crisis of 2011). However, it is generally understood that the lion's share of outside aid to North Korea now comes from China.
"After North Korea's nuclear test in February, reports indicated that China temporarily restricted its trade flows with North Korea as a means of expressing displeasure. Further provocations by North Korea could be met with reductions in both aid from – and trade with – China. But preventing the collapse of North Korea is likely to remain a priority for China, and as a result any cutbacks will need to be light enough not to endanger the survival of the regime.
"Unless the current crisis escalates into a full-scale military confrontation, it is unlikely to represent a turning point in conditions for the general population."
Does the US have any intention of resuming food aid and other assistance?
"We continue to be deeply concerned about the well-being of the people of North Korea. We currently have no plans to provide humanitarian assistance. Any decision on the provision of nutritional assistance is based on three factors: 1) the level of need in a given country; 2) competing needs in other countries; and 3) our ability to ensure that aid is reliably reaching the vulnerable populations for which it is intended."
Kelly McKellogg Swaine
US State Department spokesperson, Bureau of East Asian and Pacific Affairs
What will the effect of further sanctions be?
"Most likely to further retard access to funds and technology, certainly scare away almost all outside investment (except possibly from China), leaving most of the population stuck where it is today, economically.
"In the worst case, sanctions could end up impeding the extremely good, largely unheralded work of a number of foreign NGOs, which provide ideas, experience, and much needed materials in a wide range of humanitarian projects."
Should China, the country with the most leverage, be more proactive?
"The only country, in terms of solving the crisis, with potential for leverage is China. Its concern is that there will be a collapse in Pyongyang, and thousands of refugees would be running across the border. North Koreans, on the other hand, want the right to process and enrich their own fuel."
Carla Anne Robbins
PhD, Adjunct senior fellow, Council on Foreign Relations
Would many North Koreans flee into China if they could?
"You would see a significant uptick in the number of refugees fleeing into China if China reversed its policy tomorrow. Since Kim Jong-un took power, a real clampdown on the North Korean-China border has been seen. If they were able to cross into China uninhibited, I believe there would be a large number of North Koreans voting with their feet."
What are China's real aims?
"China is following a long-term strategy aimed at neutralising US power and influence in its neighbourhood. It has also tried to reduce the political impact the new South Korean leadership might have on North Korea with its attempted peace campaign.
"China's stand on the nuclear issue presents it with a dual opportunity – to appear constructive on the UN Security Council level, and to challenge the US presence in the region through North Korea – a proxy it can control – if it should get worse.
China's leadership is avoiding multilateralism, which the US would favour. The US, in turn, has to develop a coherent approach which goes beyond reconfirming itself as a Pacific power. At stake will be control of the region, access to oil and gas riches, maritime security in the world's most important sea lanes."
Dr Uwe Nerlich
Founding director of the Centre for European Security Strategies, Munich, Germany
Is there a solution?
"North Korea knows it has lost on this, and knows it very well. Economic success in today's environment means you need partners in the international community, which the recent events have excluded or limited.
"Kim Jong-un has put himself in a corner. He really wanted to be perceived as different. But I don't think we should exaggerate too much the fact that he was willing to change. He likely wanted limited reforms to bring economic success. Changing too much could damage the structure which maintains power (both his and North Korea's). This is part of a tit-for-tat strategy North Korea has used before. It is still going to pull this off, but at an extremely high cost.
Dr Niklas Swanström
Director, Institute for Security and Development Policy, Stockholm