The missing general, Sergei Surovikin, is the deputy commander of Russia's military operations in Ukraine. He is reported to have had advance knowledge of Wagner chief Yevgeny Prigozhin's rebellion plans and sided with him.
The Russian presidential office declined to comment on the reports and attention is now focused on whether Surovikin has been detained or not.
Sergei Surovikin was appointed general commander of Russia's invasion of Ukraine in October 2022.
Surovikin has been supporting the operation as deputy commander in chief since January when Valery Gerasimov was appointed the commander of all Russian troops fighting in Ukraine.
After joining the then Soviet military in 1983, Surovikin built a career as an officer. In 2017, he led the Russian military in its intervention in the Syrian civil war.
Known as a strict and merciless commander, he is said to be trusted by President Vladimir Putin.
Meanwhile, Surovikin has also been said to be close to Prigozhin.
The Wagner chief praised Surovikin as Russia's most capable military commander, expressing his trust in him on social media in October 2022.
In May, when Prigozhin strongly criticized the Russian defense ministry for a shortage of ammunition, he said Surovikin made all the decisions in the exchange between Wagner and the defense ministry. Surovikin may have served as a bridge between the ministry and Wagner.
It is believed the Wagner revolt was triggered by the possibility that funding would be cut unless the group came under the umbrella of the Russian defense ministry.
When the Wagner mutiny started on June 24, Surovikin attempted to bring the situation under control. He took to social media, calling on Wagner fighters not to join the rebellion and follow the will and order of the Russian president.
News outlets report on Surovikin
The New York Times on Tuesday quoted several senior US officials as saying that Surovikin knew in advance about Prigozhin's plan.
On Wednesday, the Moscow Times, an English-language newspaper in Russia, quoted a Russian defense ministry source as saying Surovikin has been detained for siding with Prigozhin.
The Financial Times, a British business newspaper, reported Thursday that Surovikin has been out of contact for several days and has been detained, citing multiple sources familiar with the matter.
A prominent Russian journalist who is critical of the Putin administration posted on social media that Surovikin has not been in contact with his family for the past three days.
Kremlin spokesperson Dmitry Peskov declined to comment to reporters on Thursday about the reported detention of Surovikin and referred them to the defense ministry.
Expert: Possibility of conflict within military and administration
Hyodo Shinji, the research director of Japan's National Institute for Defense Studies, says the focus is on whether Surovikin gave tacit approval to the rebellion and helped, in some way, those involved.
Hyodo pointed out that the mutiny was originally seen as a confrontation between Prigozhin and the Russian defense ministry and military, but there may have been a conflict deeply rooted within the military or the Putin administration.
Hyodo said its crucial to closely watch for any rift between the military and the Putin administration.
He also said the detention of Surovikin could negatively impact Russia's command control in Ukraine and cause confusion within the military and a decline in morale among the soldiers.
Rebellion supporters in Russian military
During the march on Moscow, Wagner forces are believed to have taken over a Russian military hub in the southern state of Rostov without facing any resistance.
John Sullivan served as deputy secretary of the US State Department and served as ambassador to Russia for nearly three years from December 2019 to September last year.
In an interview with NHK, Sullivan said its "difficult to understand" what happened "if there was no support for Prigozhin within the Russian military and security services."
Sullivan also commented on Russian President Vladimir Putin being weakened, saying he "wasn't strong enough to put down that revolt, arrest Prigozhin or eliminate him."
He said Prigozhin was allowed to go to Belarus because Putin "wanted to avoid chaos and bloodshed" and "had to strike a deal with a person that he labeled a traitor who had stabbed Russia in the back."
Ukrainian forces make progress
Meanwhile, the General Staff of the Armed Forces of Ukraine said Thursday its forces have been taking the initiative in the direction of Bakhmut, the stronghold in the eastern region of Donetsk, which the Russians captured in May.
It also said Ukrainian forces are conducting offensive operations on the frontlines, adding pressure to the Russian forces.
Ukraine's military intelligence chief, Kyrylo Budanov, said Thursday that Wagner forces will no longer participate in the fighting in Ukraine.
He said Ukraine's aim is to steadily advance and recapture territory amid the confusion on the Russian side.