US President Donald Trump has reacted with optimism to North Korea's announcement of its change of course and its immediate and indefinite nuclear test freeze, stating that he was "looking forward" to meeting with Kim Jong-un.

Donald Trump, who has been preparing to meet Kim in the coming weeks, welcomed the development ahead of the summit, calling it a "good news for the world."

"North Korea has agreed to suspend all Nuclear Tests and close up a major test site. This is very good news for North Korea and the World – big progress!" the US leader tweeted. "Look forward to our Summit."

North Korean leader Kim Jong-un announced at an earlier session of the ruling party that the country's further nuclear and ballistic missile tests will be frozen, starting April 21, 2018. Pyongyang also promised to shut down its main nuclear research facility.

The socialist country vowed not to use nuclear weapons unless there is a "nuclear threat or nuclear provocation" against North Korea. The North also expressed willingness to work on global non-proliferation of atomic weapons. Speaking at a plenary meeting of the central committee of the Worker's Party of Korea, Kim outlined the country's future development course, which will focus on economic growth.

The surprise announcement comes amid preparations for the much-anticipated high-level meeting between Trump and Kim, planned to take place sometime after the historic intra-Korean leaders' summit, scheduled for April 27.

As Trump's team continues to prepare for the summit, earlier this week the US president confirmed that Secretary of State nominee Mike Pompeo already had a secret meeting with the North Korean leader in Pyongyang, and that, currently, five locations are being considered for the US-Korea summit.