by Devlin Bar­rett and Tom Hays
AP

Police bol­stered secu­ri­ty in sub­ways and trains Wednes­day after the gov­ern­ment warned that al-Qai­da sui­cide bombers were con­tem­plat­ing an attack on New York’s mass-tran­sit sys­tems dur­ing the hol­i­day sea­son. An inter­nal memo obtained by The Asso­ci­at­ed Press says the FBI has received a “plau­si­ble but unsub­stan­ti­at­ed” report that al-Qai­da ter­ror­ists in late Sep­tem­ber may have dis­cussed attack­ing the sub­way sys­tem.

The inter­nal bul­letin says al-Qai­da ter­ror­ists “in late Sep­tem­ber may have dis­cussed tar­get­ing tran­sit sys­tems in and around New York City. These dis­cus­sions report­ed­ly involved the use of sui­cide bombers or explo­sives placed on subway/passenger rail sys­tems,” accord­ing to the doc­u­ment.

“We have no spe­cif­ic details to con­firm that this plot has devel­oped beyond aspi­ra­tional plan­ning, but we are issu­ing this warn­ing out of con­cern that such an attack could pos­si­bly be con­duct­ed dur­ing the forth­com­ing hol­i­day sea­son,” accord­ing to the warn­ing dat­ed Tues­day.

A per­son briefed on the mat­ter, speak­ing to The Asso­ci­at­ed Press on con­di­tion of anonymi­ty because of the sen­si­tiv­i­ty of the intel­li­gence-gath­er­ing work, said the threat may also be direct­ed at the pas­sen­ger rail lines run­ning through New York, such as Amtrak and the Long Island Rail Road, which are par­tic­u­lar­ly busy with Thanks­giv­ing hol­i­day trav­el­ers.

A fed­er­al law enforce­ment offi­cial said there’s no indi­ca­tion that any­one involved in the plan­ning is in the Unit­ed States. That offi­cial also spoke on con­di­tion of anonymi­ty because it involved intel­li­gence-gath­er­ing.

While law enforce­ment stepped up patrols around sub­ways and trains, many com­muters around the city were unfazed by the news and had not even heard of the threat.

“If you get scared that means they win,” com­muter Omid Sima said on the plat­form of the sub­way below Rock­e­feller Cen­ter. “There’s always been ter­ror warn­ings. I can’t change my life because of that.”

The Big Apple’s tight­ly packed pas­sen­ger trains and sub­way cars have long been a source of con­cern for police offi­cers — and a tempt­ing tar­get for would-be ter­ror­ists — but there is often dis­agree­ment as to how seri­ous­ly author­i­ties should take spe­cif­ic intel­li­gence reports.

The city has more than 450 sub­way sta­tions that han­dle mil­lions of com­muters every day.

A Pak­istani immi­grant was arrest­ed and con­vict­ed for a scheme to blow up the sub­way sta­tion at Her­ald Square in 2004. There was also a planned cyanide attack on the sub­ways by al-Qai­da oper­a­tives that author­i­ties say was called off in 2002; anoth­er abort­ed al-Qai­da plot to destroy the Brook­lyn Bridge in 2003; and a plot to bomb under­wa­ter train tun­nels to flood low­er Man­hat­tan, which was bro­ken up in 2006 by sev­er­al arrests over­seas.

Three years ago, author­i­ties weighed reports that bombers might try to use baby strollers to bring explo­sives into city trains. Many secu­ri­ty offi­cials lat­er con­clud­ed that was a false alarm.

NYPD spokesman Paul Browne said they have received an unsub­stan­ti­at­ed report and as a result have “deployed addi­tion­al resources in the mass tran­sit sys­tem.”

While fed­er­al agen­cies reg­u­lar­ly issue all sorts of advi­so­ry warn­ings, the lan­guage of this one is par­tic­u­lar­ly blunt.

Intel­li­gence and home­land secu­ri­ty offi­cials are work­ing with local author­i­ties to try to cor­rob­o­rate the infor­ma­tion “and will con­tin­ue to inves­ti­gate every pos­si­ble lead,” the memo says.

Rep. Peter King, the top Repub­li­can on the House Home­land Secu­ri­ty Com­mit­tee, said author­i­ties “have very real specifics as to who it is and where the con­ver­sa­tion took place and who con­duct­ed it.”

“It cer­tain­ly involves sui­cide bomb­ing attacks on the mass tran­sit sys­tem in and around New York and it’s plau­si­ble, but there’s no evi­dence yet that it’s in the process of being car­ried out,” King said.

Depart­ment of Home­land Secu­ri­ty spokesman Russ Knocke said the warn­ing was issued “out of an abun­dance of cau­tion going into this hol­i­day sea­son.”

No changes are being made to the nation’s threat lev­el, or for tran­sit sys­tems at this time, he said.

FBI spokesman Richard Kolko con­firmed only that his agency and the Home­land Secu­ri­ty Depart­ment issued a bul­letin Tues­day night to state and local author­i­ties, and the infor­ma­tion is being reviewed.And here is the rest of it.