The U.S. embassy in Russia has cautioned Americans to have evacuation plans as the crisis over Ukraine deepens, The Guardian reports.

The move drew a rebuke from the Russian foreign ministry.

In a message to Americans in Russia on Sunday, the US embassy said: “There have been threats of attacks against shopping centers, railway and metro stations, and other public gathering places in major urban areas, including Moscow and St Petersburg as well as in areas of heightened tension along the Russian border with Ukraine.

“Review your personal security plans. Have evacuation plans that do not rely on US government assistance.”

A spokeswoman for the Russian foreign ministry, Maria Zakharova, questioned if the U.S. had passed on the information about possible attacks to Russia.

“And if not, how is one to understand all of this?” Zakharova said.