Prime Minister Shinzo Abe said he and U.S. President Donald Trump agreed in telephone talks Wednesday night to continue to put pressure on North Korea over its nuclear weapon and ballistic missile programs.

Abe told reporters after the conversation that he and Trump affirmed they will maintain the pressure until North Korea seeks dialogue on the basis it will give up its nuclear program.

"We talked thoroughly about what we should do from here on to make the denuclearization of North Korea a reality," Abe said.

Abe's conversation with Trump, the second this month, followed a display of unity between North and South Korea at the Pyeongchang Winter Olympics.

It came amid concern in Tokyo that the thaw between the two Koreas could compromise efforts to maximize diplomatic and economic pressure on Pyongyang and lead to the start of dialogue on North Korea's terms, effectively accepting it as a nuclear power.

Ahead of the opening ceremony of the Olympics on Friday, Abe held talks with South Korean President Moon Jae In and confirmed the two countries will continue to work trilaterally with the United States to maximize pressure on North Korea.

But worry has spread in the Abe administration that South Korea may head into dialogue with North Korea on its own following a meeting between Moon and a high-ranking delegation from Pyongyang.

The delegation's visit to South Korea culminated in an invitation from North Korean leader Kim Jong Un for Moon to visit Pyongyang for talks.

The united front between Tokyo and Washington appears to be also under scrutiny after U.S. Vice President Mike Pence suggested in a recent interview that the United States is open to holding talks with North Korea while maintaining the "maximum pressure campaign."

In the wake of the interview that Pence gave to the Washington Post aboard Air Force Two on his way home from the Olympics, Abe and members of his Cabinet have insisted there is no change to the position shared by Tokyo and Washington, and that dialogue must not be held with North Korea until it takes concrete steps toward denuclearization.

When Abe and Trump last spoke on the phone on Feb. 2, they confirmed to work together with South Korea in putting pressure on North Korea to abandon the weapons programs.