The sister of North Korean leader Kim Jong Un, Kim Yo Jong, warned South Korea on Sunday that if its joint military plan with the U.S. goes through that it will increase tensions on the Korean Peninsula.

North and South Korea have been talking about holding a summit in an attempt to rebuild relations. The countries are still in a continued war with one another since a ceasefire in 1953.

"The two leaders have explored ways to recover relations by exchanging letters on several occasions and agreed to restore severed hotlines as the first step for that process," said South Korean President Moon Jae-in press secretary, Park Soo-hyun last Tuesday, according to KCNA, the state news agency of North Korea.

But Sunday, Kim Yo Jong said the relations between North and South Korea should only be seen as “physical ties," according to Reuters.

Washington and Seoul have plans to hold a military drill later in August. Kim Yo Jong called the action by South Korea “an aggressive war exercise.”

"Our government and military will keep a close eye on whether the South Koreans go ahead with the aggressive war exercises or make a big decision. Hope or despair? That's not up to us," Kim Yo Jong told KCNA.

President Joe Biden has stated that he won't follow former President Donald Trump's approach to North Korea and is seeking "total denuclearization" of the country. Trump's national security adviser John Bolton has said that North Korea would never give up its nuclear weapons voluntarily and that Trump was not serious about stopping the country from building nuclear weapons.