The Korean and Syrian crises will be high on the agenda for foreign ministers from the G8 group of nations, as their talks began in London.
Correspondents say Japan, present at the talks, is looking for a strong statement of solidarity over Korea.
North Korea has been making bellicose threats against South Korea, Japan and US bases in the region.
The foreign ministers will also debate the Syrian crisis and peace prospects in the Middle East.
UK Foreign Secretary William Hague welcomed the ministers to Lancaster House on Thursday morning.
He said: “We’ve got many issues to discuss today around the themes of conflict prevention and conflict resolution.
“We are going to be discussing counter-terrorism and counter-proliferation – that will give us an opportunity to discuss the DPRK (North Korea) and Iran.”
The Group of Eight nations comprises the US, Britain, France, Germany, Italy, Japan, Canada and Russia.
Britain currently holds the rotating chairmanship of the G8 and the talks are a prelude to the annual G8 summit later this year in Northern Ireland.
Missile threat
The BBC’s diplomatic correspondent James Robbins says ministers agree that the combination of warlike threats from North Korea and preparations for new missile tests amount to dangerous provocation.
“There is no disagreement with the United States over North Korea,” Russian Foreign Minister Sergei Lavrov said at a meeting with US Secretary of State John Kerry in London on Wednesday.
South Korea has raised its alert level amid indications that the North is preparing for a missile test.
Pyongyang has moved two Musudan missiles to its east coast. The ballistic missiles have an estimated 3,000km (2,000-mile) range.
Correspondents point to Monday – the birthday of North Korea’s founder Kim Il-sung – as a potential launch date.
North Korea has increased its fiery rhetoric following fresh UN sanctions imposed after its third nuclear test and joint military manoeuvres by the US and South Korea.
The North says it will restart a mothballed nuclear reactor, has shut an emergency military hotline to the South and has urged countries to withdraw diplomatic staff, saying it cannot now guarantee their safety.
UN Secretary-General Ban Ki-moon has been among those calling for calm on the peninsula.
In Washington on Wednesday, US Defence Secretary Chuck Hagel said North Korea was “skating very close to a dangerous line”, adding: “Their actions and their words have not helped defuse a combustible situation.”
Humanitarian assistance
The G8 ministers met Syrian opposition figures on Wednesday on the sidelines of the two-day forum.
Our correspondent says that, unlike North Korea, Syria divides the G8 and no-one expects Damascus’s ally Russia to join others backing punitive action against President Bashar al-Assad.
Fresh evidence of links between some opposition fighters and al-Qaeda makes it even harder for governments to decide a course of action, he adds.
In a meeting with ministers on Wednesday, leaders of the opposition Syrian National Coalition (SNC) reportedly pressed for more humanitarian assistance.
Mr Kerry, however, stressed the importance of the opposition becoming better organised, a senior US official told reporters.
In a statement issued after the talks, Mr Hague said Britain was committed to finding a political solution to the crisis.
“We discussed what further assistance the UK could provide to save lives in Syria, and how we could work together to ensure this support was channelled most effectively,” he said.
More than 60,000 people are estimated to have died since the uprising against the government of President Assad began in March 2011.
The London talks are also the first chance for G8 ministers to discuss face-to-face the failure of last week’s meeting in Almaty, Kazakhstan, on curbing Iran’s nuclear programme.
Tehran says it only wants to produce energy but the US and its allies suspect it is trying to develop a nuclear weapon.
Mr Hague, meanwhile, has said his “personal priority” for the G8 meeting is a new agreement to prevent sexual violence in conflicts.
Burma, Somalia and cyber-security are also topics on the agenda.