North Korea is being widely condemned for conducting a nuclear test Tuesday. The test poses a special challenge to North Korea's traditional ally, China.
Tania Branigan, Beijing correspondent of The Guardian newspaper, said China's patience with North Korea is wearing thin.
Beijing has summoned its North Korean ambassador, she said, and has made it very clear to North Korea that it was unhappy with the nuclear test.
China and North Korea have been suspicious of one other but the relationship is likely to continue. China is North Korea's main trading partner and supplier of aid.
"China doesn't want to destabilize the north, see a regime collapse, nor encourage refugees into China," said Branigan.