Federal authorities are boosting security in the United States after intelligence agencies detected a credible threat to Western interests overseas and the government began closing diplomatic posts in some Muslim countries, according to homeland security officials.

The Department of Homeland Security is increasing security measures at airports, train stations and other transportation hubs, and expanding scrutiny of visitors coming into the United States, two officials told ABC News.

The FBI, meanwhile, is “working sources” and taking other “logical steps” to monitor any potential threat, an FBI official said.