Special counsel Robert Mueller’s team has again delayed former White House national security adviser Michael Flynn’s sentencing hearing, a signal that Flynn is still cooperating with the ongoing Russia probe.

According to a court filing from Tuesday, the special counsel’s office claims that “due to the status” of the probe, it does not “believe that this matter is ready to be scheduled for a sentencing hearing at this time.” The next update is slated for no later than Sept. 17.

Flynn pleaded guilty in federal court in December for lying to the FBI in January 2017 about his contacts with then-Russian Ambassador Sergey Kislyak. Flynn was charged on one count of “willfully and knowingly” making “false, fictitious and fraudulent statements” to the FBI about communications exchanged with a Russian envoy.

Flynn could face up to five years behind bars for pleading guilty to lying to the FBI. However, it’s not expected that he will receive such a harsh sentence because he has complied with Mueller and the FBI.

Mueller is investigating Russian interference in the 2016 election and whether the Trump campaign colluded with the Kremlin.

[Also read: Rudy Giuliani flips?: 'No conversation' between Trump and James Comey about giving Michael Flynn 'a break']