The US Embassy in Afghanistan issued an emergency message on Tuesday warning of threats to Americans living in the capital Kabul.
"As of late February 2015, militants planned to conduct multiple imminent attacks against an unspecified target or targets in Kabul City, Afghanistan," read the message posted on the embassy's website.
It said the threats were against US citizens in Afghanistan, but there was no further information provided.
New US Defense Secretary Ash Carter visited Afghanistan on Sunday. The United States plans to cut the roughly 10,000 US troops in the country by nearly half this year and then slash them further to an embassy presence at the end of 2016.