It comes as world leaders gather for the UN General Assembly in New York
North Korea has called increased UN sanctions a 'hostile act' aimed at stifling average people's lives.
In response to fresh sanctions - imposed after the country's sixth and most powerful nuclear test - the secretive state has said that it will now develop its nuclear programme at an increased rate.
A foreign ministry spokesman for the North called the sanctions "the most vicious, unethical and inhumane act of hostility to physically exterminate the people of the Democratic People's Republic of Korea (DPRK) let alone its system and government", according to The Korean Central News Agency (KCNA).
Fresh measures - including banning textile imports and capping petrol supply - were unanimously imposed by the UN Security Council against Pyongyang one week ago.
The mandate came after North Korea successfully fired a Hwasong-12 intermediate-range ballistic missile over Japan at the beginning of September, in defiance of existing sanctions.
International tensions were then increased when Pyongyang launched a second ballistic missile across Japan two weeks later.
As North Korea responded to the sanctions on Monday, US bombers and jets conducted "mock bombing drills" over the Korean peninsula, in what was described by South Korea's Yonhap news agency as a further show of force.
A pair of B-1B bombers and four F-35 jets flew from Guam and Japan, joining four South Korean F-15K fighters as part of the latest drill.
Meanwhile Russia and China have also begun naval exercises not far from the Russia-North Korea border, to the north of Japan.
A UN General Assembly meeting will be held on on Tuesday, with North Korea's nuclear threat expected to be high on the agenda.