President Xi Jinping's sudden ousting of two generals who led his "irreplaceable" nuclear missile force has thrown a rare spotlight on a secretive Chinese unit that's crucial to any invasion of Taiwan.

The People Liberation Army's Rocket Force has evolved from a small command managing short-range missiles to overseeing the only nuclear stockpile in the world expanding in a meaningful way - and one with a direct line to China's top leader.

The sensitivity of its missile operations means Chinese state media offers few details on the rocket force. Xi's appointment of a new leadership team to spearhead the unit, however, has opened a window into its internal affairs, and all but confirmed a corruption purge at its highest echelons.

That turmoil comes as U.S. President Joe Biden wages a global campaign to throttle China's military modernization through trade controls, ostensibly to deter Beijing from invading Taiwan — an endeavor that would likely require the rocket force to bombard the island with missiles.

Here's what we know about Xi's rocket force and its leaders:

1. When was China's rocket force founded?

Prominent Chinese scientist Qian Xuesen — who later led the country's missile and space programs — proposed creating a rocket force in 1956, telling revolutionary generals it was crucial to modern warfare.

Ten years later, Premier Zhou Enlai established the Second Artillery unit to oversee China's then small stockpile of land-based, short-range missiles. Its innocuous name was designed to downplay its mission, especially as tensions simmered between China and the Soviet Union.

That cloak of secrecy remained until 1984, when the unit paraded its modern weaponry, including intercontinental missiles capable of delivering nuclear warheads, for the first time at National Day celebrations in Beijing. By 2013, the unit was fully in charge of China's nuclear arsenal and conducting precision attacks with conventional missiles, according to a defense white paper.

2. When did Xi get serious about it?

When Xi reorganized the military in 2015 — axing 300,000 personnel to streamline operations — he rechristened the Second Artillery the Rocket Force, elevating it to the same status as the army, navy and air force. That move coincided with China's territorial disputes ramping up in the South China Sea and its embrace of long-range missiles to carry multiple warheads — technology it had sat on for decades.

Xi said at its inauguration that the rocket force serves as a "strategic buttress to our country's position as a major power" and an "important cornerstone of upholding national security." The following September, the Chinese leader inspected the rocket force and praised the unit for its "irreplaceable" role in containing threats and ensuring national security. One sign of its importance in China: former Rocket Force commander Wei Fenghe became defense minister in 2018.

3. What's the Rocket Force's firepower?

While considerably smaller in size than the navy, air force or ground forces, the missile unit has nuclear deterrence capabilities critical to China's great power rivalry with the U.S. — and that's only growing.

Since its elevation in 2015, China's nuclear warhead inventory has increased by 58% to 410 as of March 2023, according to the Federation of American Scientists. While those numbers trail the U.S. and Russia, the Asian giant's nuclear stockpile is likely to reach "about 1,500 warheads" by 2035, if China continues at its current pace of expansion, according to a U.S. Department of Defense report last year.

The rocket force now runs at least 40 combat missile brigades that operate from six bases, according to a July report by the James Martin Center of Nonproliferation Studies at Middlebury Institute of International Studies in California. The authors wrote that China's dramatic multiplication of missile forces that can both reach the U.S. and be deployed regionally have "serious implications for the strategic balance in East Asia."

The crown jewel of the Rocket Force's arsenal is the DF-41 intercontinental ballistic missile. It is one of the world's longest-range missiles, capable of carrying multiple warheads and striking anywhere in the U.S.

4. How would it act in any Taiwan invasion?

If Xi decided to invade Taiwan — the self-ruled island he's said China needs to control by force if necessary — the PLA's missile command would play a crucial role. When then-US House Speaker Nancy Pelosi visited Taipei last August, China fired 11 ballistic missiles during military drills protesting her trip, including several that passed over the island.

Taiwan's Defense Ministry said in April it was observing China's rocket force, after the PLA simulated precision strikes on the island in retaliation for President Tsai Ing-wen's trip to the U.S.

The rocket force also positioned DF-17s, a medium-range ballistic missile, about 250 miles from Taiwan's coastline, according to the Middlebury report. In an attack, these weapons could strike Taiwanese air defenses fast, giving its military "as little warning time as possible."

5. What about the leadership purges?

The intrigue began when reports emerged claiming former Rocket Force chief Li Yuchao and two of his deputies were being investigated for corruption after dropping from public view. China hasn't commented on their cases, but the probe rumors were bolstered when state media announced Wang Houbin, previously deputy commander of the navy, had replaced Li as the force's commander.

Li's inclusion in the Communist Party's powerful Central Committee just last October suggested he'd been intended to stay in that role longer than 16 months.

Xu Xisheng, of the air force's Southern Theater Command, became the Rocket Force's political commissar, according to state media, replacing Xu Zhongbo, who hadn't been named in unconfirmed media reports of a corruption probe.

China analysts said the appointment of rocket force outsiders to key roles suggested Xi was trying to clean house. The overhaul came as Xi voiced calls to strengthen military leadership and the PLA launched a probe into corruption cases going back more than five years.

6. How bad is it for Xi?

Corruption among the top leaders would deal another blow to Xi's signature campaign to clean up the PLA that's spanned nearly his entire tenure. It began in 2014, when China opened investigations into some of its top current and retired generals, including two vice chairs of the Central Military Commission, the body that oversees the PLA.

That campaign rumbled on with the 2019 sentencing of Fang Fenghui to life in prison for taking bribes. Fang, who once sat on the CMC, had been one of China's most visible officers — accompanying Xi to his first meeting with former President Donald Trump in Florida in 2017.

Xi's seeming determination to push ahead with corruption purges suggests a willingness to risk near-term impact on effective war-fighting to address a core problem, said Tai Ming Cheung, director of the University of California Institute on Global Conflict and Cooperation.

But with a stated goal of building a modern military by 2027, he added, Xi now has "a short window of opportunity to clean the military house."

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