The following post was written by Xu Yangjingjing, Gu Jinglu and William Wan.

BEIJING -- After two years of rumors and anticipation, China’s Communist Party finally announced their investigation into former security czar Zhou Yongkang, the highest-ranking leader to be taken down in more than two decades.

Zhou spent much of the last decade as one of China’s most powerful people, controlling every aspect of the domestic security apparatus and maintaining deep, lucrative ties to China’s oil sector. By targeting him, Xi is breaking an unwritten party rule against going after current or former standing committee members.

As we detailed last month, the branch now in charge of Zhou’s investigation is one of the party’s most secretive and feared agencies. (Read more here for exactly how the anti-corruption agency works and the steps Zhou’s case will likely now move through.)

But in many ways, his case is unprecedented, prompting more many questions about what’s to come. To explain and analyze where this is headed and what it all means, we talked to political analysts both within and outside China.

Why is the Party doing this? 

“This shows the Party showing its legendary survival instinct. The Party is trying to navigate China over a treacherous transition to middle income status where the core challenges are no longer just pumping out GDP growth but really dealing with tough socio-political issues. This necessitates party discipline, and unity. You have to put the party first and show loyalty. So having a sort of dual loyalty as Zhou and those like him did between his own little cashed up nexus and the Party corporately is no longer possible. Zhou himself showed disloyalty in 2012 during the fall of Bo Xilai. Today he gets his payback. This is the sign of a Party leadership with a very deep sense that they need to have more legitimacy, and that they need to being ruthlessly disciplined if they are going to survive.” – Kerry Brown, professor of Chinese politics at University of Sydney.

What are the risks for Xi in publicly going after Zhou?

“There’s a danger to doing this, a danger that he now becomes the common enemy of these major clans in the party who control large portions of the party, economy and government.  People like Li Peng and Zeng Qinghong in the energy sector for example are very exposed."—Willy Lam, a Hong Kong political analyst

Why was the Zhou investigation announced at the same time as an upcoming October meeting of party leaders?

“If you look carefully, the announcement says the fourth plenum will be focus on law and rule of law and process. It’s a signal being given that this time the anti-corruption campaign is different. We are looking at institutionalization of process.” —Robert Kuhn, a businessman who has personal ties with many senior Chinese leaders

“It’s a way to steer the narrative away from this criticism of Xi as an authoritarian, megalomaniacal Mao figure, and casting his actions, including (the investigation of ) Zhou, as moves toward saving and changing the party.” – Chris Johnson, former top China analyst for CIA, now at Center for Strategic and International Studies

What does this mean to Xi Jinping and his rule?

“For Xi, it will build up his personal authority. But honestly it’s difficult for any political alliance to be formed now. And every official is worried about his own fate and they are very passive in fulfilling their duties.—Li Datong, political commentator and former editor of Freezing Point, a weekly supplement of China Youth Daily

“It means that Xi gained the upper hand in this duel within the party. It is a significant victory for him and the crack-down on tigers will continue."–Zhang Lifan, an independent historian and son of a former minister in China

What does it mean for the anti-corruption campaign?

“No matter what the leadership’s intention was with the anti-corruption campaign, the movement has gathered its own momentum and might be difficult for anyone to control where it goes. The decision [to bring down Zhou] will only get Xi more support than opposition. But it would be dangerous for Xi  to stop here, because people will be discontent, and it would look like a political maneuver rather than genuine effort to weed out corruption.”—Bao Tong, former secretary of the late premier Zhao Ziyang

“Anti-corruption is a dead-end. Because the soil is bad. The system is bad. It’s not the officials who are corrupted, it’s the system. Sure, you can get rid of some corrupted officials, but more corrupted ones will come up. And it’s impossible that the authorities would change the system, because it would mean giving more power to the people to oversee those in power. We’ve reached the end of the anti-corruption campaign, bringing down a [former] standing committee member. The public is not stupid.”—Li Datong, Chinese political commentator