North Korea warned of “tougher countermeasures for self-defence” after the UN Security Council unanimously imposed its strongest-ever sanctions on Pyongyang.

The country’s foreign ministry issued a statement on Thursday calling the UNSC’s move “another excess of authority and violation of the DPRK’s sovereignty”, referring to its official name, the Democratic People’s Republic of Korea.

“Many countries – including all the permanent member states of the UNSC – have so far conducted thousands of nuclear tests and rocket launches, but the UNSC has never prevented them from doing so,” said the ministry’s statement carried on state-run Korean Central News Agency.

The new sanctions resolution on Wednesday, which was spearheaded by the US and came after three months of tough negotiations with fellow veto-wielding council member China, passed by a 15-0 vote.

“[US President Barack] Obama and his lackeys are sadly mistaken if they calculate that they can force the DPRK to abandon its line of nuclear weaponisation and undermine its status as a nuclear power through base sanctions to pressurise it,” it said.

North Korea insists its nuclear weapons are a deterrent to US “aggression” and has brushed aside earlier sanctions, which have notably targeted its weapons exports and access to financial markets.

The resolution demands that North Korea “abandon all nuclear weapons and existing nuclear programmes” and takes aim at the state’s exports of coal – its top external revenue source.

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Under the resolution, North Korea will be restricted from exporting beyond 7.5 million tonnes of coal in 2017, a reduction of 62 percent from 2015.

Samantha Power, the US ambassador to the UN, said the resolution would strip the regime of more than $700m in hard currency, dramatically reducing the money it can spend on nuclear and ballistic weapons.

Power, speaking to reporters with her counterparts from US allies South Korea and Japan, called the resolution “the strongest sanctions regime the Security Council has imposed on any country in more than a generation”.

“So long as the DPRK makes the choice it has made, which is to pursue the path of violations instead of the path of dialogue, we will continue to work to increase the pressure and defend ourselves and allies from this threat,” said Power.

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China is North Korea’s primary ally and one of the few markets for its coal.

China has traditionally protected North Korea diplomatically, believing that Kim Jong-un’s regime is preferable to its collapse, but has grown increasingly frustrated by the neighbouring state’s defiance.

China’s UN ambassador, Liu Jieyi, reiterated that Beijing “strongly opposes” the North Korean nuclear tests – but also made a veiled criticism of joint military exercises between the United States and South Korea.