Secretary of State John Kerry raised concerns with Russia over news a general from Iran's hardline Revolutionary Guard Corps visited Moscow in defiance of a U.N. travel ban.
Fox News reported Iranian Quds Force commander Qassem Soleimani traveled to Moscow Thursday to meet with Russian President Vladimir Putin and other high ranking officials, his second trip since July.
Kerry raised the matter in a conversation Friday with Russian Foreign Minister Sergey Lavrov, according to the State Department.
The Quds Force has been responsible for killing hundreds of American troops in Iraq. Soleimani is subject to a five-year U.N. travel ban.
He cut short his trip to just one day and returned to Iran after it was revealed that he violated U.N. Security Council resolutions, sources tell Fox News.
"Such travel, if true, would be a violation" and a "serious matter of concern," State Department spokesman John Kirby said. He didn't outline Lavrov's response to Kerry on the call.
In July, five days after Soleimani's first visit to Moscow, Kerry was asked if the Iranian general would ever receive sanctions relief as part of a deal with Iran. "Under the United States' initiative, Qassem Soleimani will never be relieved of any sanctions," Kerry testified on Capitol Hill.
The CIA declined comment on the matter when reached by Fox News Friday.
Fox News' Lucas Tomlinson and The Associated Press contributed to this report.