WASHINGTON (AP) — President Joe Biden spoke Wednesday with the wife of detained WNBA player Brittney Griner, who is on trial in Russia, and assured her that that he is working to win Griner’s freedom as soon as possible, the White House said.

Biden’s conversation with Griner’s wife, Cherelle Griner, followed Brittney Griner’s personal appeal to the president in a handwritten letter from the basketball player the White House received on Monday. In the letter, Griner acknowledged her fears that she would spend forever in detention in Russia and asked Biden not “forget about me and the other American Detainees.”

Griner has been detained for four months and is currently on trial in Russia, accused of possessing vape cartridges containing cannabis oil.

“The President called Cherelle to reassure her that he is working to secure Brittney’s release as soon as possible, as well as the release of Paul Whelan and other U.S. nationals who are wrongfully detained or held hostage in Russia and around the world,” the White House said in a statement. “He also read her a draft of the letter the President is sending to Brittney Griner today.”

Biden offered his support to the family and committed to making sure they receive “all possible assistance” while the administration pursues steps to win Brittney Griner’s release, the White House said.

Griner is in the midst of a trial in Russia that began last week after she was arrested on Feb. 17 on charges of possessing cannabis oil while returning to play for her Russian team. The trial is scheduled to resume Thursday.

Fewer than 1% of defendants in Russian criminal cases are acquitted, and unlike in U.S. courts, acquittals can be overturned.

Cherelle Griner told “CBS Mornings” in an interview Tuesday that it was “disheartening” to her that she had yet to hear from Biden during Brittney Griner’s detention.