The United States on Thursday condemned Russia's detention of an American journalist writing for The Wall Street Journal and said it was seeking consular access.
US officials said they were in touch with the family of detained journalist Evan Gershkovich as well as the newspaper and that the State Department had contacted Russia.
"The targeting of American citizens by the Russian government is unacceptable. We condemn the detention of Mr. Gershkovich in the strongest terms," White House Press Secretary Karine Jean-Pierre said in a statement.
"I want to strongly reiterate that Americans should heed the US government's warning to not travel to Russia. US citizens residing or traveling in Russia should depart immediately."
President Joe Biden had been briefed on the detention, the White House said.
Secretary of State Antony Blinken in a statement connected the detention to the crackdown on media in Russia, whose relations with Washington have nosedived since the invasion of Ukraine.
"In the strongest possible terms, we condemn the Kremlin's continued attempts to intimidate, repress, and punish journalists and civil society voices," Blinken said.
Gershkovich is believed to be the first foreign journalist to be detained on suspicion of spying in post-Soviet Russia.
White House national security spokesman John Kirby said he understood that journalists must take risks and do so knowingly.
"We respect that, but it doesn't change our deep concern about the presence of Americans" still in Russia, Kirby told reporters.
Several other US citizens are in jail including Paul Whelan, a former Marine, who was arrested in 2018 and handed a 16-year sentence on espionage charges that he denies.
"This is not a new tactic for Mr. Putin and for Russian officials to detain foreigners and particular Americans," Kirby said.
"It's certainly not new for Mr. Putin to strike back against a free and independent press," he said.
Whelan's brother voiced sorrow over Gershkovich's detention and called on the Biden administration to prioritize releasing detained Americans.
"Whatever it takes, I hope the US government moves quickly and decisively so that Paul and Mr. Gershkovich are able to return to their families and loved ones soon," David Whelan said in a statement.
Russia and the United States, despite high tensions, have carried out recent prisoner swaps including one that led to the release of US basketball star Brittney Griner.