The Biden administration is using "toned-down" rhetoric against North Korea to help prevent any unnecessary escalation of tensions before its ongoing review of how to deal with the North concludes, a news report suggested Tuesday.

Citing unidentified senior administration officials, NBC News reported that "senior officials" of the administration have agreed to use "toned-down" rhetoric when speaking publicly about North Korea.

The report also said officials at the National Security Council had complained to the Justice Department about labeling North Korea as a "criminal syndicate with a flag" when the department indicted three North Koreans on cybertheft charges in February.

"A senior official said aides at the National Security Council 'were not pleased with the choice of language' and expressed concern to the Justice Department that it was 'going to provoke North Korea,' " it said.

"Biden's national security team decided early last month to take a softer public tone toward North Korea after it concluded that provoking Pyongyang while the new administration's policy is under review would be counter to US goals," it added.

The Biden administration has remained reticent in directly addressing North Korea or the security risks it poses, often citing its ongoing policy review.

Such reluctance again became apparent after North Korean leader Kim Jong-un's sister, Kim Yo-jong, blasted the US and South Korea for their joint military exercise on Monday.

The sister also said the Biden administration had better not engage in such hostile activities "if it wants to sleep well for the next four years."

White House spokeswoman Jen Psaki said she had no direct comment or response.

"Our objective is always going to be focused on diplomacy and on denuclearization in North Korea," she told reporters, according to a White House pool report.

When asked to respond at a joint press event with his Japanese counterpart in Tokyo, Secretary of State Antony Blinken too declined to offer any reaction, only noting he was aware of the message from the North Korean leader's sister.

The top US diplomat is currently on an Asia trip that will later take him to South Korea for talks with his South Korean counterparts. He will also be joined by Defense Secretary Lloyd Austin and his South Korean counterpart for a two-plus-two meeting.

The latest threat from North Korea, however, comes after "multiple" attempts by the new US administration to reach out to the North.

"I can confirm that we have reached out. We obviously have a number of channels as we always have had that we can reach out through," Psaki told a press briefing on Monday, adding North Korea has yet to respond to any US attempts to engage.

Blinken earlier said the ongoing policy review will identify all options available to the US in dealing with North Korea, allowing or making sure the US is using the best tools available.

Sung Kim, acting assistant secretary of state for East Asian and Pacific affairs, has said the review will likely be completed within weeks. (Yonhap)