The US State Department said it was told Russia has accumulated tanks and artillery at deployment sites that may be given to separatist fighters in Ukraine.
The US also has its own information that Russia redeployed military forces to its border with Ukraine, State Department spokeswoman Jen Psaki said.
"We have information that additional tanks have been prepared for departure," she added.
More top news
Stephen Port, 41, is already accused of drugging and murdering four men he met on gay websites before dumping their bodies near a church.
Nicola Sturgeon said it is her job as Scottish First Minister "to explore every option to protect Scotland's interests" in Europe.
New England manager Sam Allardyce believes he is the right man for the job, ten years after being turned down by the Football Association.