South Korea on Saturday announced plans to strengthen its missile deterrence capabilities, as part of its response to North Korea's recent missile launches.

US President Donald Trump and his South Korean counterpart, Moon Jae-in, had made the decision to revisit bilateral guidelines governing Seoul's missile programme during a phone call on Friday, Moon's office said.

The two leaders had "agreed in principle" to strengthen Korea's defences in order to "counteract the provocations and threats of North Korea and to revise the missile guidelines to the level desired by [South Korea]," a statement said.

In line with a bilateral agreement with the United States, South Korean missiles are currently limited to a range of 800km and a maximum payload of 500kg. Seoul wants to increase the payload to a tonne.

READ MORE: All the latest updates from the North Korea tensions

The White House made no specific mention of the guidelines but said the two leaders had agreed "to strengthen our alliance through defence cooperation and to strengthen South Korea's defence capabilities".

Trump had also given his "conceptual approval" for the planned sale of billions of dollars of US military equipment to South Korea, the White House said.

The US currently has around 28,500 soldiers stationed in South Korea, and Washington also guarantees the country's protection under its nuclear umbrella.

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North Korea escalated regional tensions once again this week by firing a ballistic missile over Japan in defiance of UN resolutions and fresh sanctions imposed last month which are expected to slash its export revenues by a third.

That launch came after Pyongyang tested two intercontinental missiles in July and claimed to have the US mainland within its range.

North Korea also became embroiled in a war of words with Trump, threatening to fire missiles at the US Pacific territory of Guam, while the US president threatened Pyongyang with "fire and fury".