President Trump's legal team has begun preparing answers to written questions posed by special counsel Robert Mueller's team, sources directly involved in the process say.

There is no timetable for the written responses to be returned to Mueller's office, since the answers have not yet been shared with Mr. Trump — a necessary step before the legal team replies to Mueller. A meeting with the president to discuss the written responses could occur next week, sources said. CNN first reported the president's legal team had begun crafting answers.

Mueller's office recently sent about 15 questions to Mr. Trump's legal team as part of a negotiated process to address the issues related to candidate Trump, Russia and campaign encounters that are part of Mueller's investigation. The two sides agreed to have Mueller send questions on the campaign-era issues that would be answered in writing, the sources said.

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This dialogue has been ongoing for months, and the written responses appear to be the first tangible response to Mueller from Mr. Trump.

Whether Mueller will request answers to another round of written questions remains unclear. Sources close to the process said both sides will revisit that issue after Mr. Trump's answers have been received by the special counsel. No agreement has been reached on any face-to-face meeting between Mr. Trump and Mueller or his team.

Mr. Trump's legal team has made it clear to Mueller that it considers off-limits questions about Mr. Trump's actions as president, including his firing of FBI Director James Comey and his tweets, citing the president's authorities under Article II of the Constitution. It is unclear whether a legal dispute over the president's constitutional prerogatives would push Mueller to seek a subpoena to compel Mr. Trump's testimony, a move that would almost certainly be challenged in court by the president's lawyers.