South Korea is announcing tougher sanctions on the Democratic People's Republic of Korea over its nuclear and missile activities. This comes amid already heightened tensions, as Seoul and Washington begin their largest-ever joint military exercise.

Lee Suk-joon, from the South Korean Office for Government Policy Coordination, is making the announcement. The DPRK has warned of preemptive nuclear attacks on the US and South Korea in response to their joint military exercises. Pyongyang's National Defense Commission said the army and people will launch an "all-out offensive". It says the first target will be South Korea's presidential office Chongwadae, and the second target, the White House and the US mainland.

Last week, the DPRK fired short range missiles into the sea off its eastern coast. The action came after the UN Security Council passed new sanctions on the country, which is the toughest in 20 years.