A first-class terror threat

LIKE GHOSTS of autumns past, old feelings of confusion and unease sprang up in the minds of many Americans yesterday as authorities scrambled to thwart a host of planned terrorist attacks.

For much of the day, only vague snippets of information leaked about an overseas plot that involved synagogues, explosive packages and cargo planes - including two UPS jets that landed in Philadelphia International Airport in the early morning.

By nightfall, the unnerving episode came into focus, and this much was clear: the U.S. had been the target of what President Obama called a "credible terrorist threat," and it was unclear if the threat had been fully averted.

Authorities uncovered packages from Yemen on cargo planes in England and Dubai, United Arab Emirates, that contained the powerful industrial explosive PETN, U.S. officials said. The packages were addressed to two Chicago-area synagogues.

The shocking discovery prompted officials to search cargo planes up and down the Eastern seaboard, including UPS planes that landed at airports in Philadelphia and Newark, N.J.

Karen Cole, a UPS spokeswoman, said the planes that landed at Philly International had departed from Paris and Cologne, Germany.

Cole said she couldn't confirm if the planes contained packages from Yemen. She noted, however, that the Transportation Safety Administration cleared all of the items on the UPS planes searched in Philadelphia and Newark.

"Security is hugely important to us," Cole said. "The fact that the questionable shipments were caught is an example that the security systems that we have in place are working."

Parts of the plot might remain undetected, Obama's counterterror chief warned. "The United States is not assuming that the attacks were disrupted and is remaining vigilant," John Brennan said at the White House.

Obama's sobering assessment unfolded four days before midterm elections in which the discussion of terrorism has played almost no role. The president went ahead with weekend campaign appearances, including a stop at Temple University today.

He is also scheduled to attend a rally in Chicago today, and stay at his home there - which is across the street from a synagogue. Officials told the Chicago Tribune that neither of the explosive devices were addressed to that synagogue.

The terrorist efforts "underscore the necessity of remaining vigilant against terrorism," the president said.

U.S. officials said they were increasingly confident that al Qaeda's Yemeni branch, the group responsible for the failed Detroit airliner bombing last Christmas, was responsible for yesterday's attempted attack.

Al Qaeda, which is active in the Arab nation, has long made clear its goal of launching new attacks on the United States.

Authorities in Dubai intercepted one explosive device. The second package was aboard a plane searched in East Midlands, north of London, and officials said it contained a printer toner cartridge with wires and powder. Brennan said the devices were in packages about the size of a breadbox.

Obama didn't specifically accuse Yemen's al Qaeda branch, but Brennan called it the most active al Qaeda franchise and said that anyone associated with the group was a subject of concern.

The radical U.S.-born Muslim cleric Anwar al-Awlaki, who now is in hiding in Yemen, is believed to have helped inspire recent attacks, including the Fort Hood shooting, the Times Square bombing attempt and the failed Detroit airliner bombing. Another American hiding in Yemen, Samir Khan, has declared himself a traitor and has helped produce al Qaeda propaganda.

Authorities believe that about 300 al Qaeda members or cells operate in Yemen.

The Yemeni government has stepped up counterterrorism operations, with help from the U.S. military and intelligence officials. Mohammed Shayba, general director of the state airline's cargo department, said the government is conducting an investigation.

"Those in charge are in constant meetings and they are investigating and taking the issue seriously," he told the Associated Press.

Intelligence personnel had been monitoring a suspected plot for days, officials said. The packages in England and Dubai were discovered after a Saudi Arabian intelligence picked up information related to Yemen and passed it on to the U.S., one official said.

U.S. intelligence officials warned last month that terrorists hoped to mail chemical and biological materials as part of an attack on America and other Western countries using the mail. The alert came in a Sept. 23 bulletin from the Homeland Security Department and obtained by the Associated Press.

In the hours following the discoveries, Yemeni officials and Scotland Yard were investigating and the U.S. issued a 72-hour ban on all cargo from Yemen.

This report includes information from Daily News wire services.