North Korea has fired a missile over northern Japan in a move Japanese Prime Minister Shinzo Abe called an “unprecedented” threat to his country. The missile, launched early on Tuesday Korean time, flew over Hokkaido island before crashing into the sea. The UN Security Council is expected to hold an emergency meeting in response. North Korea has conducted a flurry of missile tests recently, but this is the first time it has fired what is thought to be a ballistic weapon over Japan. On the two previous occasions its rockets crossed Japan – in 1998 and 2009 – North Korea said they were for satellite launch vehicles, not weapons. The BBC’s Rupert Wingfield-Hayes in Tokyo says this latest launch appears to be the first of a missile powerful enough to potentially carry a nuclear warhead.