Israeli president Reuven Rivlin has written to Russian leader Vladimir Putin to ask him to pardon an Israeli-American who was jailed for drug smuggling.

Russian authorities found 9 grams of marijuana in Naama Issachar’s luggage during a layover between flights from India to Israel. She told her sister she accidentally left it in her bag when flying home, and she has now been sentenced to seven-and-a-half years.

The charge was initially cannabis possession, but it was upgraded to drug smuggling. Rivlin has been speaking to her family, and he agreed to write a letter to Putin asking him to consider a pardon.

He said she admits to making “a grave mistake”, but he added that such a long sentence could have a “terrible” impact on her life. “Because of the particular and individual circumstances of Naama Issachar’s case, I am appealed to the president’s mercy and compassion with a request for his personal intervention to grant her an extraordinary pardon,” said Rivlin.

Isaachar was born and raised in New Jersey and moved to Israel at 16. She had been travelling after completing a period of military service for Israel.

Her family claims that she is being punished disproportionately to pressure Israel into freeing a Russian held in Israel on a U.S. extradition request. Another American caught with cannabis in Russia was fined 15,000 rubles ($230) by a Russian court and released because she had spent several weeks in custody while awaiting a court hearing.

Some commentators claim that Isaachar has been used as a political pawn in an effort to free the Russian held in Israel. Alexei Burkov is in the process of being extradited to the U.S., where he is suspected of committing cyber offenses.

Rivlin thanked Putin for Russia’s help in locating the remains of an Israeli soldier killed by Syrian forces in a 1982 battle, and urged him to show mercy to Isaachar. Putin will consider the request once it arrives via the diplomatic channels.