The United States is working with other countries to make sure foreign airlines have armed air marshals aboard when flying over or into American airspace, Homeland Security Secretary Tom Ridge (search) told Fox News on Tuesday.
"I think it is well-recognized now that making sure air travel is safe is not just a concern and priority for the United States," Ridge said on "Fox and Friends." "It needs to be a concern and priority for the entire international community."
Noting that countries such as France and Britain are supporting the effort wholeheartedly, Ridge said, "I think it's well-recognized that we're all in that together."
Under the new flight restrictions put in place Monday to prevent a possible Al Qaeda (search) attack, foreign airlines may be denied access to American airspace if they refuse to place armed marshals on flights. The mandate is effective immediately.
"Any sovereign government retains the right to revoke the privilege of flying to and from a country or even over their airspace," Ridge said in announcing the mandate on Monday. "So ultimately a denial of access is the leverage that you have."
Ridge also said the nation would remain at orange alert (search) through the New Year's holiday and perhaps for a few more weeks.
"We are as concerned today as we were yesterday [Sunday]," he said. "We'll be concerned as much this week as we were last week."
The new directive requires selected international flights that enter U.S. airspace to carry an armed law enforcement officer aboard. DHS will require such officers on airplanes where intelligence information leads to a specific concern.
U.S. security officials have feared that Al Qaeda operatives would again hijack planes to use them as missiles. The most recent concerns centered on airliners or cargo planes that take off from overseas and cross over U.S. airspace, either on their way to a U.S. airport or to a foreign one.
State of Heightened Alert
The Bush administration raised the terrorism alert level to orange, or high, on Dec. 21, citing nonspecific but credible threats of an imminent terrorist attack.
Ridge told Fox News the national terror level was raised because of a combination of the holiday season and information regarding possible specific threats.
There were "several streams of reporting" on possible attacks regarding timelines and continuing discussion from "multiple sources, credible sources" about threats, Ridge said, and information with "credibility greater than we've seen before" about a possible attack.
Air France canceled six flights between Paris and Los Angeles on Wednesday and Thursday after security discussions between U.S. and French officials. Ridge told Fox News on Tuesday that U.S. officials spoke with the French delegation on Monday about how to better share information to avoid such cancellations.
French Transport Ministry spokesman Olivier Mousson said U.S. security agents have inspected security at French airports since the United States raised its alert level.
Aviation security experts said the announcement marks a significant change in that, up until now, international security guidelines have been voluntary.
"In the past, no country has ever tried to impose on other countries any measures of aviation security," said Rafi Ron, president of New Age Security Solutions, a Washington-based consultancy, and the former security director for the Israeli Airport Authority.
Ron predicted that the measure will be enforced without much resistance because of the huge importance of the U.S. market to foreign carriers.
The next logical step will be for the international community to push for global aviation security standards, including mandated reinforced cockpit doors and better airport perimeter defenses.
DHS reviews the passenger and crew manifests of all planes bound for U.S. airspace, generally after the plane has taken off, because passenger lists are usually finalized only minutes before the plane taxis from the gate, said department spokesman Dennis Murphy. Some passenger lists are reviewed beforehand.
The directive comes in the form of three emergency amendments to air security regulations involving cargo planes, passenger planes and airliners passing over U.S. airspace. There are thousands of international commercial and cargo flights daily involving U.S. airspace and hundreds of international carriers.
Armed government officers from the country of the airline's ownership would be aboard, and they be equipped to prevent anyone from reaching the plane's cockpit and to communicate with the crew, Murphy said.
The U.S. government would help train air marshals for countries without a program of their own.
"We would rather have our allies and friends put their trained sky marshals on those flights," Ridge told Fox News. If they can't, Ridge said "we would say, that's just fine with us … but I think at the end of the day, the rest of the world would prefer to train their own air marshals."
Some international airlines said Monday they would cooperate with the new U.S. requirement. Others, including airlines in Canada and Germany, said they already were using armed marshals on some flights.
Britain said Sunday it had tightened security for trans-Atlantic flights and suggested, as it has in the past, that it might put armed sky marshals on some planes.
Terror Threat on the Seas?
Meanwhile, there were reports that Al Qaeda has turned its terror sights to the sea, targeting luxury cruise liners in an expansion of its "jihad" against the West.
Owners of the recently launched $1.3 billion Queen Mary 2 on Sunday confirmed threats of terror hang over its maiden voyage early next year. But a spokesman for QM2 owner Cunard told Foxnews.com that reports of threats against the ship were unsubstantiated, and that the company was working with authorities on both sides of the Atlantic to monitor the situation.
"We're well aware of the concerns people have around the Queen Mary" Ridge told Fox News on Tuesday, adding that the U.S. Coast Guard will work with the ocean liner to boost security as needed.
"We are concerned about aviation security, but day in and day out, whether we're at [terror threat level] orange or not, we have flights and patrols over our ports, we have more patrols of our borders," Ridge said.
Fox News has also confirmed that the airspace over the Las Vegas Strip will be restricted New Year's Eve.
Las Vegas has been mentioned as a possible terrorist target, but officials have yet to say that was the reason behind the ban.
Authorities are expecting more than 200,000 people to flock to the Strip this New Year's Eve.
Noting that governors, mayors and police chiefs, as well as federal officials, have boosted personnel and security measures during the heightened alert, Ridge said, "there are visible signs of increased security but ... there are invisible increases in security as well, on the ground and in the air."
Fox News' Mike Emanuel, Liza Porteus and The Associated Press contributed to this report.