U.S. President Joe Biden approved a classified nuclear strategic plan in March, reorienting Washington's deterrent strategy on China's nuclear arsenal expansion for the first time, according to the New York Times.

The White House never announced that Biden had approved the revised strategy, titled the "Nuclear Employment Guidance," the newspaper reported.

An unclassified notification to Congress of the revision is expected to be sent before Biden leaves office, the newspaper reported.

In recent speeches, two senior administration officials were allowed to allude to the strategy revision, the newspaper reported. The strategy is updated every four years or so, the newspaper added.

"This administration, like the four administrations before it, issued a Nuclear Posture Review and Nuclear Weapons Employment Planning Guidance," said White House spokesperson Sean Savett.

"While the specific text of the Guidance is classified, its existence is in no way secret. The Guidance issued earlier this year is not a response to any single entity, country, nor threat."

The remarks, however, fell short of raising serious concerns in Beijing on Wednesday.

"The U.S. is peddling the China nuclear threat narrative, finding excuses to seek strategic advantage," Chinese Foreign Ministry spokesperson Mao Ning said.

"China is seriously concerned about the relevant report and the facts have fully proved that the United States has constantly stirred up the so-called China nuclear threat theory in recent years," she added.

'Major driver'

Daryl Kimball, executive director of the Arms Control Association, said that while U.S. intelligence estimates suggest China may increase the size of its nuclear arsenal from 500 to 1,000 warheads by 2030, Russia currently has some 4,000 nuclear warheads "and it remains the major driver behind U.S. nuclear strategy."

Kimball cited June remarks by one of the officials referred to in the Times report, White House Senior Director for Arms Control, Disarmament, and Nonproliferation Pranay Vaddi.

According to those remarks, the U.S. strategy was to pursue nuclear arms restraints with China and Russia, but if China continued on its current trajectory and if Russia exceeds New START limits, the U.S. at some point in the future may need to consider adjustments to the size and makeup of its nuclear force, Kimball said.

"My understanding is that the point at which the current administration thinks it might want to consider such changes won't come until 2030, or some time after," he said.