Biden speaks to family of WSJ reporter, says detention by Russia is 'totally illegal'

President Joe Biden spoke to the family of Evan Gershkovich, a Wall Street Journal reporter who the United States says is being unjustly imprisoned by Russia, White House Press Secretary Karine Jean-Pierre told reporters aboard Air Force One on Tuesday.

The president "felt it was really important to connect with Evan's family," Jean-Pierre said.

"We're making it real clear that it's totally illegal what's happening," Biden told reporters on the tarmac as he boarded the plane to depart for a state visit to Ireland.

The State Department announced on Monday that Gershkovich, who was arrested on espionage charges in late March that the U.S. adamantly denies, is now officially classified as a wrongfully detained American, a designation that grants additional powers and resources to U.S. officials as they work to secure his freedom.

The Gershkovich said that it was encouraged by both the State Department's announcement and the president's call.

"We appreciate President Biden's call to us today, assuring us that the U.S. government is doing everything in its power to bring him home as quickly as possible," the statement said. "In addition to being a distinguished journalist, Evan is a beloved son and brother. There is a hole in our hearts and in our family that won't be filled until we are reunited."

But John Kirby, the White House's National Security Council spokesperson, said this was just the beginning of what could be a lengthy battle to bring Gershkovich home.

"The determination of wrongful detention, it doesn't start the clock necessarily on communicating with the Russians about getting him released. We're very early in this process here," he said.

American diplomats have still not been able to gain access to Gershkovich in detention -- a violation of longstanding agreements between Russia and the U.S. and international law, according to the State Department.

Secretary of State Antony Blinken and the U.S. ambassador to Russia have both spoken to their counterparts about Gershkovich's case.

Kirby declined to disclose any details about conversations with the Russian government, but he said that officials within the administration were "certainly having discussions about what we can do to get him released."

Russian officials have charged Gershkovich with espionage. Gershkovich denies the charges and his lawyers filed for an appeal, which is scheduled to be heard in Moscow later this month.

ABC's Justin Gomez and Ellie Kaufman contributed to this report.