(CNN) -- Canada is immediately limiting carry-on items for flights to the United States in the aftermath of a failed terror attack on a Northwest Airlines flight.
"Effective immediately, U.S.-bound passengers are not allowed to bring carry-on bags into the cabin of the aircraft, with some exceptions," said a statement from Transport Canada.
According to the agency, carry-ons will be limited to medication or medical devices, small purses, cameras, coats, infant-care items, laptop computers, containers carrying life-sustaining or special-needs items, musical instruments, or diplomatic or consular bags. Crutches, canes and walkers also are permitted.
"These measures are expected to be in place at least for several days," Transport Canada said.
Umar Farouk AbdulMutallab, 23, is charged with attempting to destroy a Northwest Airlines flight from Amsterdam, Netherlands, to Detroit, Michigan, on Christmas Day. He attempted to ignite an explosive device sewn into his underwear, authorities say.
AbdulMutallab, a Nigerian who had a multiple-entry visa to the United States, had been added to a watch list of 550,000 potential terrorist threats. But "the info on him was not deemed specific enough to pull his visa or put him on a no-fly list," a U.S. official said.
AbdulMutallab first boarded a KLM flight from Lagos, Nigeria, to Amsterdam. Both Nigerian authorities and KLM, a Northwest partner, say he received secondary security screening. But a U.S. official said Friday that AbdulMutallab was not checked for traces of explosives using a more extensive test.
The Transportation Security Administration had invoked a so-called "one-hour rule" after the thwarted attack, sources told CNN.
The rule prohibited passengers on international U.S.-bound flights from leaving their seats during the last hour of a flight, the sources said. Passengers had to stow pillows and blankets, and maps viewed on in-flight entertainment screens were disabled during the final hour of flight.
TSA has since modified the rule, giving airlines and crews discretion over implementation, sources said.
"When we were landing in the U.S. we couldn't get up or have anything on our laps," said Rati Lavanig, who traveled from Thailand with her small child. "It was difficult because right at the end he wanted some milk, and I couldn't give it to him."
Several international airlines posted advisories on their Web sites regarding extra screenings and carry-on bags for international U.S.-bound flights, saying that the U.S. government's revisions have prompted changes for passengers flying to the United States.
Only one carry-on bag is allowed for international U.S.-bound flights, the advisories said. Virgin Atlantic advised passengers to check in early; British Airways told passengers to check in normally.
Passengers traveling across the United States braced for long lines and delays, as well.
Barry and Angela Szczesny arrived at the airport in Detroit, Michigan, three hours ahead of their flight to Washington -- far earlier than they'd usually allow for a domestic flight.
In Detroit, long lines at the ticket counters greeted Delta and Northwest passengers early Tuesday, but subsided by around 8 a.m.
Security lines were long but moved, forcing passengers to wait only about 15 minutes.
CNN's Allan Chernoff, Taylor Gandossy and Sandra Endo contributed to this report