Pete Souza/The White House
President Barack Obama meets with members of his national security team in the Situation Room of the White House, in a handout photo provided by the White House.
Law enforcement officials in the United States, England, Dubai and elsewhere are investigating several suspicious packages sent from Yemen to the United States — at least two of which the White House says contained "explosive materials."
The packages were addressed to synagogues in Chicago. Details are still emerging — our earlier coverage of the investigation can be found here.
Here's how the story has developed:
Update at 6:56 p.m. ET: Early tests show the seized packages contain the powerful industrial explosive PETN — the same chemical used in the 2009 Christmas attack, U.S. officials have told the AP. The tests have not been confirmed.
The AP is also citing an anonymous official who says the packages were intercepted in England and Dubai after Saudi Arabia's intelligence service gave information related to Yemen to the United States.
Our original post: "Obama Says Packages Were A 'Credible Terrorist Threat' To U.S."
Authorities are investigating several suspicious packages sent from Yemen to the United States, in what President Obama calls a "credible terrorist threat." The cargo packages were intercepted by security personnel overseas.
Speaking at the White House Friday afternoon, Obama said that two packages intercepted in Dubai and England late Thursday appear to contain explosive materials. The packages were addressed to synagogues in Chicago.
Friday morning, agents from the FBI and Transportation Security Administration inspected UPS cargo planes at Philadelphia International Airport and New Jersey's Newark airport.
And then Friday afternoon, U.S. fighter jets escorted a United Arab Emirates flight to a safe landing at New York City's John F. Kennedy Airport. The flight had originated in Dubai; it reportedly contained cargo from Yemen.
According to a White House statement, President Obama was informed of the security alert at 10:35 Thursday night, and he has received updates throughout the investigation.
That has led many to speculate that U.S. officials had received advance word of a pending attack. At Friday's briefing, Deputy National Security Adviser for Homeland Security and Counterterrorism John Brennan would not clarify how the intelligence came to law enforcement officials' attention.
Brennan said, "Whenever you pull a string, there is a reason why you’re pulling that string."
Last month, a Homeland Security Department memo obtained by the Associated Press warned that terrorists may try to mount an attack on the U.S. and other Western countries using the mail.