Tokyo wants to strengthen an international alliance against Pyongyang as tensions rise over its nuclear weapons programme
Officials from North and South Korea hold further talks over Pyongyang's plan to participate in next month's Winter Olympics.
South Korean President Moon Jae-In says in order for peace in the region, North Korea must demilitarise.
"Any use of nuclear weapons by the North will be met with a massive military response that is both effective and overwhelming," said US Defence Secretary Jim Mattis.
North Korea has reinforced its ground and missile defences along its east coast.
White House says N.Korea's claim that President Trump has declared war is 'absurd'
Trump, North Korea leaders trade increasingly threatening insults
The flight was the farthest north of the demilitarised zone separating North and South Korea that any US fighter jet or bomber has flown in the 21st century, the Pentagon said.
North Korea ups the ante by threatening an H-bomb test in the Pacific, while Kim Jong-un calls President Trump a "dotard" he will "tame with fire".
Former US Secretary of State John Kerry and NATO's former chief, Anders Fogh Rasmussen speak exclusively to Euronews on the escalating threats from North Korea
Moon Jae-in made the comments at a joint media conference with Vladimir Putin.
The South Korean navy has begun manoeuvres in the Sea of Japan which are meant, analysts say, to deter the North from any action at sea.
The mood in South Korea after North Korea launched its sixth and largest nuclear test was unsurprisingly more tense than usual.
North Korea fires several short-range missiles into the sea off its east coast according to US military, as South Korea and the US conduct annual joint military drills.
Japan has begun moving its defence system to the west of the country after North Korea announced plans to launch ballistic missiles near the US Pacific territory of Guam.
Just a few days ago the US territory of Guam was the ideal place to ignore the world’s problems. That was before it became a target for North Korea’s
US President Donald Trump has warned North Korea that his 'fire and fury' comment over the country's development of nuclear weapons may not strong enough.
War of words intensifies as North Korea says its plan to strike the US Pacific territory of Guam will be ready by mid-August.
US Secretary of State has said America is not North Korea's enemy and welcomes dialogue with Pyongyang.
North Korea says it has successfully test fired a long-range intercontinental ballistic missile.
Ordered and supervised by leader Kim Jong