Two men were arrested late last night at a New York airport trying to board separate flights to Egypt on their way to Somalia.
The US Attorney for New Jersey said 20-year-old Mohammed Mahmood Alessa and 24-year-old Carlos Eduardo Almonte, both from New Jersey, were arrested at John F Kennedy International Airport.
They were charged with conspiring to commit an act of international terrorism by waging 'violent jihad' through Al Shabaab, a youth movement tied to al-Qaeda.
Federal officials said there was no active plot and the pair, who had been under surveillance since October 2006 following a tip from an acquaintance, did not pose an immediate threat.
The men are due to appear tomorrow in federal court in Newark, New Jersey.
According to the complaint filed by the US attorney, an undercover New York Police Department Intelligence Division officer recorded several meetings with the suspects starting in 2009 in which they expressed intent to kill people abroad, and possibly in the US.
If convicted, the suspects face a maximum penalty of life in prison.