The UN Security Council on March 7 imposed new sanctions against North Korea amid escalating tensions as the North threatened a pre-emptive nuclear strike against the US. The council unanimously passed a resolution, agreed by the US and China, which added new names to the UN sanctions blacklist and tightened restrictions on the North's financial dealings, notably its "bulk cash" transfers. These will "bite hard," the US ambassador to the United Nations, Susan Rice, said. Unperturbed, North Korea announced it was voiding non-aggression pacts with South Korea and severing a hotline with Seoul.