Hidden Chinese tests bolster ‘nuclear warfighting’

NEWS AND ANALYSIS:

China detonated a secret underground nuclear blast in 2020 that was detected by a seismic station in Kazakhstan and was aimed at improving Beijing’s nuclear war fighting, according to a senior State Department arms control official.

Christopher Yeaw, assistant secretary of state for arms control and nonproliferation, disclosed new details of the Chinese test that the Trump administration says violated Beijing’s self-imposed moratorium on tests under an unratified test ban treaty.

Some arms control experts had originally questioned whether the blast even took place, but Mr. Yeaw said the test’s time and place were confirmed by a seismic monitoring station in Makanchi, in southern Kazakhstan.

President Trump announced recently that the U.S. would resume nuclear tests on an equal basis with those of China and Russia. Both nations have been detected conducting underground blasts.

The underground blast in China registered as a 2.75 magnitude on the seismic scale and its signature was “not consistent with an earthquake,” Mr. Yeaw said.

“There is very little possibility that it is anything other than an explosion, a singular explosion,” the former chief scientist at the Air Force Global Strike Command said in remarks Tuesday at the Hudson Institute.

Additionally, China used a testing method called decoupling to hide the test from international monitors.

Nuclear test decoupling is an evasion technique involving a nuclear detonation in large, deep underground cavity that seeks to muffle the explosion’s seismic signature.

Six years later, China is preparing for another nuclear test with a yield of up to “hundreds of tons” of explosive power, Mr. Yeaw said.

Mr. Yeaw, quoting the late nuclear scientist C. Paul Robinson, said if U.S. adversaries conduct nuclear tests with explosive yields while the U.S. maintains a strict, zero-yield testing policy, “the United States would be living at an intolerable disadvantage.”

“I love that quote, because that’s exactly what’s happening, intolerable disadvantage,” Mr. Yeaw said. “And what President Trump has said in an equal basis is we’re not going to play on a nonlevel playing field anymore.”

Russia has also engaged in covert nuclear testing while maintaining that it is adhering to a moratorium, he said.

The extent of the type of reciprocal testing planned by the U.S. will be up to the president, Mr. Yeaw said.

He said the Chinese and Russians gain key strategic advantages from hidden blasts that boost their “nuclear war fighting capabilities.”

“This is a serious matter …. We see a modernization and expansion of the theater nuclear forces in Russia and China,” he said. “I think we should be particularly alarmed that potentially these types of super-critical yield-producing nuclear tests flow right into those capabilities,” he said.

In Vienna, Robert Floyd, executive secretary of the multinational Comprehensive Nuclear-Test-Ban Treaty Organization, confirmed that the blast was detected as “two very small seismic events” near China’s Lop Nur nuclear test site.

The tests, however, appear to be below the threshold of 500 tons of explosive power needed for the organization to detect a nuclear blast.

China’s Foreign Ministry has denied engaging in covert underground nuclear testing.

Mr. Yeaw said President Trump is seeking a better international agreement that includes both China and Russia and that could prevent a new nuclear arms race.

Past arms pacts with the Soviet Union and Russia were violated producing strategic disadvantages for the U.S., he said.

China so far is refusing to join new talks with the U.S. and Russia on reducing arms despite what Mr. Yeaw said was a massive nuclear buildup that is “beyond breathtaking.”

Mr. Trump wants China in any future arms treaty and Mr. Yeaw said as with similar attempts during the first administration new three-way talks will be difficult to convene.

China has a legal and binding obligation under Article Six of the Nuclear Nonproliferation Treaty to enter into good faith negotiations toward disarmament, Mr. Yeaw said.

Beijing needs to take that commitment as seriously as its large-scale nuclear buildup that Mr. Yeaw said is growing in leaps and bounds.

“It’s an expansion the world has not seen in many decades…ever since the early days of the Cold War,” he said. “So they have an obligation to become involved and the world needs to stop giving them a pass on that.”

Trump says a decision soon on Taiwan arms sales

President Trump this week commented on recent demands by Chinese President Xi Jinping regarding Beijing’s opposition to U.S. arms sales to Taiwan and said a decision on the matter could be made soon.

Mr. Xi told the president in a Feb. 4 phone call that the U.S. must handle the issue of arms sales to Taiwan “with prudence.”

Asked about Mr. Xi’s warning during a press gaggle on Air Force One on Monday, Mr. Trump said, “I have a response. I’m talking to him about it.

“We had a good conversation and we’ll make a determination soon,” the president said, fueling speculation on a possible cutback in new arms transfers.

Taiwan remains a major flashpoint in U.S.-China relations despite an emerging détente between Washington and Beijing following Mr. Trump’s meeting with Mr. Xi in Busan, South Korea, in October.

Two months later, the Trump administration announced plans to sell $11.1 billion in new arms to the democratic-ruled island state that China has vowed to annex. It was the largest arms sale in years.

The sale includes HIMARS — or high-mobility artillery rocket systems — as well as howitzers, Javelin anti-tank missiles, Altius loitering munition drones and parts for other equipment, according to the Taiwan Defense Ministry.

Analysts suspect Beijing will seek concessions on arms sales to Taiwan as part of Mr. Trump’s pursuit of a trade deal with China.

The president adopted a softer stance on China after Beijing imposed new restrictions on its exports of rare earth minerals needed for both commercial and military industry.

During the phone call earlier this month, Mr. Xi told Mr. Trump that China views Taiwan as the most important issue in China-U.S. relations.

The two leaders are set to meet in Beijing in April.

U.S. arms sales are governed the 1972 Taiwan Relations Act, which calls for supplying defensive arms, and three joint U.S.-China communiques that led to formal diplomatic relations with Beijing.

One 1982 communique states that arms sales to Taiwan were not resolved in the talks leading up to the normalization of diplomatic ties with China.

An internal note from then-President Reagan on the communique states that any curb in arms sales to Taiwan “is conditioned absolutely upon the continued commitment of China to the peaceful solution of the Taiwan-PRC differences.”

Also, the quality and quantity of U.S. arms sales to the island is “conditioned entirely on the threat posed by the [People’s Republic of China].”

“Both in quantitative and qualitative terms, Taiwan’s defense capability relative to that of the PRC will be maintained,” Reagan said. “It should be clearly understood that the linkage between these two matters is a permanent imperative of U.S. foreign policy.”

U.S. military commanders have said Mr. Xi has ordered the People’s Liberation Army to develop forces capable of annexing Taiwan by 2027

Meanwhile, Chinese military threats to Taiwan have escalated sharply in the recent years with large-scale provocative war games near the island that the commander of the U.S. Indo-Pacific Command Adm. Sam Paparo has called “rehearsals” for an invasion.

China fears U.S. bomber strikes on nuclear site

China reacted with unease to the daring U.S. military raid on Iran’s nuclear facilities with official state media voicing fears that underground Chinese nuclear sites are vulnerable to similar strikes, according to a U.S. Air Force think tank report.

The June 22 operation known as Midnight Hammer involved B-2 bombers and Tomahawk cruise missiles that blasted three main Iranian nuclear facilities.

The bombers flew undetected from the U.S. and dropped GBU-57 bunker-buster bombs, inflicting significant damage to the Fordo, Natanz and Isfahan nuclear sites.

Despite China’s significant economic ties to Iran and the two countries’ strategic partnership, Beijing’s response to the attack was relatively muted, the report said.

The U.S. long-range precision attack against hardened military targets in the heart of an adversary state raises concerns that China needs to upgrade both its long-range strike capabilities and its defenses.

This underscores that the operational success of the Midnight Hammer strikes may have stirred up broader concerns in PRC defense circles over the security of China’s own nuclear deterrent capabilities,” the report said.

Chinese strategists have expressed long-held views about advanced American conventional precision-strike capabilities, “particularly the threat they could pose to China’s nuclear deterrent,” the report said.

China’s nuclear build-up has been described by U.S. officials as a massive expansion of warheads, missiles, bombers and submarines.

Shortly after the June bombing raid, state broadcaster China Central Television interviewed a PLA engineering professor who said China needed to develop advanced defenses to protect its underground nuclear infrastructure from attack.

China also lacks the offensive firepower of the precision-guided bunker buster bombs.

“PRC concerns over its deterrence capabilities could also intensify as a result of the U.S. decision to pursue advanced strategic missile defense through the ’Golden Dome’ system and nuclear modernization,” the report said.

Much of China’s nuclear facilities are hidden in large, underground tunnels and factories that has been called the Great Underground Wall. The complex was largely secret until disclosed publicly in 2015 as including some 3,000 miles of tunnels.

In 2023, the Pentagon for the first time disclosed new details of China’s underground nuclear and weapons facilities that an annual report on the Chinese military said were expanding.

Bunkers and tunnels used for PLA nuclear warhead and missile storage, and command and control facilities are being modernized, the report said.

China “has thousands of [underground facilities] and constructs more each year. These UGFs are central to the PRC’s counter-intervention and power projection efforts, enabling the PLA to protect valuable assets from the effects of missile strikes and to conceal military operations from adversaries,” the report said.

Officially, China’s government denounced the strikes on Iran as a “dangerous display of hegemony” and reckless misuse of military power.

• Contact Bill Gertz on X @BillGertz.