U.S. President Donald Trump on Tuesday defended his policy toward North Korea in response to media reports that U.S. intelligence believes the North's leader Kim Jong Un has no intention of giving up nuclear weapons despite his pledge to denuclearize.

In a Twitter post, Trump said, "All of Asia is thrilled" by his engagement with North Korea. "Only the Opposition Party, which includes the Fake News, is complaining."

"If not for me, we would now be at War with North Korea!" he wrote.

[Getty/Kyodo]

Trump said "many good conversations with North Korea" are "going well" following his historic summit with Kim last month. But he did not provide details about those conversations.

The president made the remarks ahead of talks between U.S. Secretary of State Mike Pompeo and Kim in Pyongyang later this week, in what will be the first high-level bilateral meeting after the Trump-Kim summit on June 12 in Singapore.

During the summit, Kim committed to the "complete" denuclearization of the Korean Peninsula while Trump promised to provide security guarantees to Pyongyang.

Given a lack of specifics on denuclearization in the leaders' agreement, Pompeo and Kim are expected to discuss concrete and credible measures to rid Pyongyang of nuclear weapons and ballistic missiles.

Speaking at a press briefing Tuesday, State Department spokeswoman Heather Nauert declined to set a timeline for denuclearization of North Korea ahead of Pompeo's travel to Pyongyang.

"I know some individuals have given timelines. We're not going to provide a timeline for that," Nauert said.

"The secretary's looking forward to having his meetings," she said. "A lot of work is left to be done, certainly. We go into this with eyes wide open, with a very clear view."

Trump's national security adviser John Bolton said Sunday he expects Pompeo to discuss with North Korea a plan to dismantle its nuclear weapons and ballistic missile programs in a year.