The dismissal of Anatoly Serdyukov was a surprise because the burly politician was widely regarded as having the president’s blessing for a military modernization that has won the enmity of generals and arms makers with connections to members of Putin’s inner circle.

Adding intrigue was the fact that Serdyukov is married to the daughter one of Putin’s close allies, a former prime minister who wields enormous influence as chairman of state-run natural gas giant Gazprom. Media reports suggest that Serdyukov’s alleged philandering angered Viktor Zubkov and may have been a factor in the sacking.

But most experts see a behind-the-scenes power struggle at the root of Putin’s decision.

Serdyukov has masterminded a campaign to drastically cut the ranks of officers and overhaul an antiquated military structure to create a leaner, meaner force that might restore Russia’s faded military glory.

In particular, he has aggressively demanded higher quality and cheaper prices from the military industry — ruffling powerful business interests. That is seen as having set off an internal struggle in which Kremlin allies of leading arms makers have conspired to bring Serdyukov down.

“He angered the leaders of defense industries, refusing to sign new contracts until they make their prices fully transparent,” said Alexander Golts, an independent Moscow-based military expert. “And he told them that the military will buy the weapons it needs, not the weapons they want to sell.”

Dmitri Trenin, director of the Carnegie Moscow Center, told The Associated Press that Serdyukov’s moves to “replace the very foundation of the Russian military system” won him powerful enemies.

“A lot of entrenched interests benefited from that system,” Trenin said.

Putin made the announcement in a meeting with Moscow regional governor Sergei Shoigu, whom he appointed as the new minister. Some observers predict that Shoigu may take a less radical approach to military reform.

While giving few details, the president linked the move to a probe announced by the country’s top investigative agency last month into the sale of military assets, including real estate. The Investigative Committee says the state suffered damages of 3 billion rubles ($95 million) in just a few cases reviewed.

The corruption case first surfaced last month and involves Oboronservice, a state-controlled company whose activities include servicing military aircraft and arms and building military facilities.

In the course of the probe, investigators carried out an early morning search of the apartment of Yevgeniya Vasilyeva, a senior Oboronservice official who was once a close aide of Serdyukov in the Defense Ministry. Serdyukov reportedly was alone at the apartment with Vasilyeva when police turned up — fueling rumors of an affair.

“The scandal behind the scandal is a personal scandal that has been rumored in Mr. Serdyukov’s family,” Trenin said.

Serdyukov, a former furniture salesman, entered public service as a tax official and quickly rose through the ranks to become head of the Russian tax service before being appointed defense minister in 2007. Russian media have speculated that he owed his meteoric rise to marrying Zubkov’s daughter.

Whatever the origins of Serdyukov’s success, it’s clear that he made a profound impact on Russia as its military chief.

Serdyukov’s reform led to the dismissal of 200,000 officers, disbanded nine out of 10 military units and turned over once untouchable military assets to civilian hands.

“Serdyukov’s reform marked a break with the Russian military culture,” said Golts. “Russian military officers simply can’t imagine a different military model.”

Under Serdyukov, the military purchased amphibious assault vessels from France, bought Israeli drones, Italian armored vehicles and other foreign weapons in an unprecedented slap in the face of the Russian military industrial complex.

“He has made powerful foes by ending purchases of obsolete weapons,” said Igor Korotchenko, a retired colonel of Russia’s military general staff who is now editor of National Defense magazine.

He said that a battle for the distribution of 20 trillion rubles ($635 billion) that the Kremlin plans to spend on buying new weapons through 2020 was likely a key reason behind Serdyukov’s firing.

Speculation about Serdyukov’s possible downfall has floated around for years, but he had received Putin’s staunch backing until now. Putin authorized and publicly praised Serdyukov’s reforms, and some observers expect that they will continue, although perhaps at a slower pace, under his successor.

“The continuation of the military reform is inevitable,” Korotchenko said. “Radical changes that have been made in the command system and the structure of the military can’t be reversed.”

But others warned that Shoigu, who had served as the nation’s Emergency Situations minister for two decades before being appointed regional governor half a year ago, would likely face strong pressure from the top brass to take a less radical approach to military reform.

“The new boss will have to take a new approach differing from that of his predecessor,” said Golts, “and that would create a good opportunity for those who want to stop this reform.”