The conversations between lawyers for Donald Trump and his former campaign manager Paul Manafort would not be covered by attorney-client privilege -- and the president's lawyer Rudy Giuliani could be forced to appear before a grand jury because of it.

NBC News reported that cooperation between the president's legal team and that of his indicted former campaign manager could amount to obstruction of justice depending on what was discussed.

If Manafort's lawyers revealed confidential information related to his cooperation with special counsel Robert Mueller or if Trump's team dangled the prospect of a pardon before him, it could be considered witness tampering, legal experts who spoke to NBC said.

Under typical rules, the report noted, a joint defense agreement like that which Giuliani revealed to multiple news agencies earlier in the week would be protected by attorney client-privilege.

However, experts who spoke to NBC said "a joint defense agreement can only exist between people who have a common legal interest" -- and that common legal interest evaporated when Manafort began cooperating with Mueller in his investigation of Trump.

"When former national security adviser Michael Flynn flipped," NBC noted, "he notified Trump's lawyers that he was withdrawing from their joint defense agreement."

Former U.S. attorneys Joyce Vance and Mimi Rocah, both NBC analysts, agreed that Trump and Manafort no longer had a shared legal interest once the former campaign manager began cooperating with the special counsel.

"If I were Mueller I would be issuing subpoenas today to Rudy Giuliani and [Manafort's attorney] Kevin Downing, and anyone else involved in those communications, so they would have to explain under oath exactly what was conveyed," Vance said.

She added that the situation is highly unusual and troubling.

"The whole idea that we are talking about a president having a joint defense agreement with 32 other people — because they are all under criminal investigation — is not normal, and we can't let it become normal," Vance said.