President Donald Trump sent North Korean dictator Kim Jong-un an "excellent" personal letter, the state-run news, Korean Central News Agency (KCNA), reported on Sunday. Kim said he would "seriously contemplate" Trump's proposal, although the content of the letter is unknown, the Associated Press reported.

"A letter was sent by President Trump and correspondence between the two leaders has been ongoing," White House Press Secretary Sarah Huckabee Sanders said.

South Korea's Office of the President "evaluates the exchanges of personal letters between the leaders of the United States and North Korea positively from the perspective of continuing the momentum of the US-North Korea talks," the office said in a statement.

Although formal peace talks between Kim and Trump ended after a summit in February, Kim has sent multiple personal letters to Trump over the last few months. Earlier this month Trump said Kim sent him a "beautiful" letter, but again, the contents were unknown. Trump also said Kim sent a "birthday card," which was hand delivered a day before his actual birthday.

The United States is continuing to push North Korea to abandon its nuclear arms before international sanctions are lifted. North Korea, however, wants a step-by-step process, where sanctions are slowly dropped as denuclearization takes place.

The letters are vital, especially as peace talks continue. Trump is scheduled to meet with South Korean President Moon Jae-in, Business Insider reported. The South Korean presidential office said they believe the letters are a positive step in keeping the peace talks alive.

Word of the letter came days after Kim met with Chinese President Xi Jinping. KCNA reported Kim and Xi agreed on important issues that impact the Korean Peninsula.

Trump and Xi are expected to meet during the G-20 Summit next week. Analysts anticipate Xi to provide Trump with a message from Kim about the peace talks.

During his New Year's speech, Kim said he would find a "new way" if the United States didn't remove sanctions and pressure from North Korea. When the meeting in February failed, Kim gave Trump until the end of the year to salvage the negotiations. Specifically, Kim said he wanted to see mutually acceptable terms for a deal. The United States said Kim was to blame for the negotiation breakdown because of his desire for sanctions relief even though he only wanted to partially surrender its nuclear capabilities.