WASHINGTON (REUTERS) - The Pentagon said on Monday (Aug 7) that it was reviewing bilateral ballistic missile guidelines with South Korea that could allow Seoul to have more powerful missiles as tensions with North Korea rise over its missile and nuclear programmes.

Under the current guidelines, last changed in 2012, South Korea can develop missiles up to a range of 800km with a maximum payload of 500kg.

US President Donald Trump's attempts to pressure North Korea into abandoning its nuclear ambitions have so far gained little traction, and Pyongyang has only stepped up its tests, launching two intercontinental ballistic missile (ICBM) tests last month.

"There is currently a limit on the warhead size and missiles that South Korea can have and yes, it is a topic under active consideration here," Pentagon spokesman Captain Jeff Davis said.

"I would tell you that we would be favourably inclined to do anything which furthers the defence capabilities of South Korea and we certainly have seen our alliance change and adapt over time before," Captain Davis said.

The Pentagon said it had received the request to review the guidelines from South Korea and the military is working with the State Department to determine the best way forward.

The UN Security Council unanimously imposed new sanctions on North Korea on Saturday aimed at pressuring Pyongyang to end its nuclear programme. The sanctions could further choke North Korea's struggling economy by slashing its US$3 billion (S$4 billion) annual export revenue by a third.