The US Embassy in Moscow is asking American citizens to leave Russia immediately, while there is still a limited supply of commercial travel options.
In a security alert published on Tuesday evening, the embassy indicated that dual American-Russian nationals could be drafted into the Russian army or banned from leaving Russia.
"Russia may refuse to acknowledge dual nationals’ U.S. citizenship, deny their access to U.S. consular assistance, prevent their departure from Russia, and conscript dual nationals for military service," it said.
The memo further states that commercial flight options are "extremely limited" and often unavailable at short notice. "If you wish to depart Russia, you should make independent arrangements as soon as possible," read the warning posted online, noting that the embassy itself was limited in its ability to assist US citizens.
The embassy discouraged U.S. nationals from going to Russia and urged those who reside there or travel to the country to leave it as soon as possible, while limited options still exist.
The alert further recalled that the rights to peaceful assembly and freedom of expression were not guaranteed in Russia. It added that the US State Department was advising US nationals to avoid protests and not to photograph security personnel during demonstrations.
US citizens attending rallies have been arrested by Russian authorities, the security alert confirmed.
Several hundred people have been arrested in Russia in recent days during demonstrations against the mobilisation of reservists to fight in Ukraine, decreed last week by President Vladimir Putin.