The level of security for American Samoa has been raised to the second highest status.
The Director for Homeland Security, Leiataua Birdsall Alailima, says the alert has gone form a significant terrorism threat to a high risk threat.
There will be increased checks of people entering and leaving the airport and port, security will also be heightened at ports of entry.
Police surveillance of key facilities and offices will also be increased.
Immigration, customs and agriculture inspections for visitors as well as cargo entering the territory will be more stringent.
The national US Security Director, Governor Tom Ridge, has raised the security alert because intelligence reports indicate that Al Qaeda attacks are planned for so-called soft targets such as hotels, apartments and fuel companies.