WASHINGTON -- The White House expressed cautious optimism Wednesday after a meeting between the North Korean and Chinese leaders, saying "things are moving in the right direction."

North Korean leader Kim Jong-un and Chinese President Xi Jinping met in Beijing this week ahead of Kim's planned summits with South Korean and US leaders this spring.

US President Donald Trump tweeted earlier in the day he "received message" from Xi Tuesday night that the meeting "went very well" and that Kim "looks forward to his meeting with me."

At a regular press briefing, White House press secretary Sarah Sanders was asked to characterize the administration's mood.

"Certainly we're going to be cautiously optimistic, but we feel like things are moving in the right direction and that the meeting yesterday was a good indication that the maximum pressure campaign has been working," she said, referring to international sanctions designed to force Pyongyang to talk about denuclearizing.

"You saw him leave for the first time to -- since becoming the leader of North Korea, leaving his country for the first time for that meeting," Sanders noted. "And we consider that to be a positive sign that the maximum pressure campaign is continuing to work. And we're going to continue moving forward in this process in hopes for a meeting down the road."

Trump has said he will meet with Kim before the end of May to discuss the regime's denuclearization.

"Certainly, we would like to see this," Sanders said. "Obviously, this is something of a global importance, and we want to make sure that it's done as soon as we can, but we also want to make sure it's done properly, and we're working towards that goal."

China's ambassador to Washington visited the White House on Tuesday to inform national security officials of Kim's trip, according to Sanders. The officials then briefed the president.

She declined to elaborate on what was in the personal message from Xi to Trump.(Yonhap)