Russia offered condolences to Iran on Friday over the killing of Qassem Soleimani, commander of the elite Quds Force.
The U.S. confirmed Thursday that it carried out a strike that killed Soleimani in Iraq.
"We consider the murder of Soleimani as a result of an American missile strike on the outskirts of Baghdad as an adventurous step that will lead to an increase in tension in the entire region. Soleimani has faithfully served the cause of protecting the national interests of Iran. We express our sincere condolences to the Iranian people," the Russian Foreign Ministry said in a statement.
Iran's leadership vowed to avenge the death with the country's Supreme Leader Ayatollah Ali Khamenei saying a "bitter revenge" awaits the perpetrators.
Soleimani was the long-time commander of the Revolutionary Guards Corps Quds Force, which has been designated as a terror group in the U.S. since 2007. The group is estimated to have 20,000 members.
Shortly after the airstrike, President Donald Trump posted the U.S. flag on Twitter with no comment.
The Pentagon accused Soleimani of planning to carry out attacks on U.S. diplomats and service members in Iraq and the region, saying the slain leader was responsible for the deaths of hundreds of Americans and coalition service members.
