North Korea television confirmed this morning that the country had successfully carried out a third nuclear test, the first since Kim Jong-un took power. An international monitoring agency in Austria said the explosion was twice as big as North Korea’s previous test in 2009, despite allegedly involving a smaller, “more advanced” device.

North Korea’s foreign ministry has threatened even stronger action — though it didn’t say what — if the United States kept up its hostility.

The BBC’s Jon Sudworth in Beijing says a test like this would have cost billions of dollars and that’s money North Korea really needs to feed its own citizens. The country has struggled to feed its own people and regularly needs food aid in order to stave off famine.

The test has been strongly condemned in the region. South Korea and Japan are pushing for even harsher sanctions. According to Sudworth, the Chinese response is harder to read. On paper the Chinese government has strongly condemned the North Koreans, but Sudworth suggests that some military hawks in China may welcome a little sabre-rattling by its closest regional ally as a message to the U.S.