Trump says 'very happy' with progress in North Korea talks

US President Donald Trump said Monday he was "very happy" with how talks were progressing with North Korea, as observers and the media highlight the lack of concrete results one month after his summit with Kim Jong Un.

"A Rocket has not been launched by North Korea in 9 months. Likewise, no Nuclear Tests. Japan is happy, all of Asia is happy," Trump tweeted.

"But the Fake News is saying, without ever asking me (always anonymous sources), that I am angry because it is not going fast enough. Wrong, very happy!"

Trump appeared to be referring to an article in The Washington Post on Sunday that claimed the president was frustrated with the lack of immediate progress, despite his public statements claiming the talks were a success

The article cited unnamed White House aides, State Department officials and diplomats.

Trump hit out at the Post in a series of tweets on Monday, saying the paper, which is owned by Amazon boss Jeff Bezos had "gone crazy against" him.

"In my opinion the Washington Post is nothing more than an expensive (the paper loses a fortune) lobbyist for Amazon," Trump said.

In a joint declaration after his historic summit with Trump on June 12 in Singapore, the North Korean leader "reaffirmed his commitment" to work towards the "denuclearization of the Korean Peninsula."

But the actual details of the process, including how and when the North's nuclear programme is to be dismantled, have yet to be hammered out.

A month ago, the US administration insisted on the "urgency" of denuclearization, and said it would begin "very quickly."

"We're hopeful we can get it done" by 2020, before the end of Trump's term, Secretary of State Mike Pompeo said at the time.

Pompeo has been charged with the challenge of putting meat on the bare bones of the Singapore commitment.

But 40 days and one apparently fruitless visit by Pompeo to Pyongyang later, the tone of the American side has clearly changed.

"We have no time limit," Trump told reporters last week. "We have no speed limit."

Asked about the change in tone, State Department spokeswoman Heather Nauert sought to reassure: "We have teams in place that are working very hard on this issue every day," she said.

"We have said there's a lot of work left to be done."