Two new big corruption cases have been opened in Russia just days after a graft investigation brought down the minister of defense.

Investigators said Friday that about $200 million has been stolen from a troubled space agency program and that about $3 million was skimmed off the budget for an international economic summit held in Vladivostok in September. Roman Panov, who is head of the Perm Territory and was involved in preparing for the summit, was detained by police Friday, the Interfax news agency reported.

Other high-level officials are involved, investigators told the RIA Novosti news agency.

Running three major, well-publicized, simultaneous criminal investigations into corruption is without precedent here. The probes come as President Vladimir Putin’s public ratings have sagged and as rumors about a potentially debilitating back injury persist.

Some analysts believe Putin has decided he needs to show the government taking decisive action to shore up his standing, and corruption is a handy issue. According to this argument, the graft investigations are more a means to a political end than a pursuit of justice for its own sake.

Sergei Stepashin, head of the government’s auditing agency and not particularly an ally of Putin’s, told Interfax that his staff had sent evidence of the space program embezzlement to criminal investigators a year ago. It could be coincidence that the probe is just becoming public now, or it could be evidence of a coordinated anti-corruption campaign.

The space agency program, called Glonass (Global Navigation Satellite System), is an attempt to create a Russian alternative to the American global-positioning system, GPS. It has been plagued with technical failures.

“There is no doubt that the government is interested in this inquiry and the exposure of corruption in the Glonass program’s implementation,” said Russian Deputy Prime Minister Vladislav Surkov, a key Putin loyalist.

The Vladivostok summit, attended by Secretary of State Hillary Rodham Clinton, was seen by Russia as a chance to host a successful international event in its most important Pacific Coast city. Shortly before the summit convened, a specially built highway collapsed, though it was repaired in time for the conference.

Last week, police raided the offices of a Defense Ministry offshoot, and investigators said they believed $100 million in property had been illegally sold off. That led to Defense Minister Anatoly Serdyukov’s firing Tuesday. His replacement, Sergei Shoigu, got Putin’s permission Friday to replace the armed forces’ chief of the general staff, Gen. Nikolai Makarov.

Taking over from Makarov will be Col. Gen. Valery Gerasimov. Several other top generals were also shifted to new posts.