Is there a case for extending a “no-fly” ban to all suspect individuals?

Umar Farouk Abdulmutallab was placed on the US’s 550,000-name extended watchlist, known as the Terrorist Identities Datamart Environment (Tide), after his father alerted authorities. That might back the case for putting all Tide suspects on a no-fly list. But it would also potentially open the way for malicious reporting by anyone with a grudge against an individual. An unwieldy and inaccurate list could defeat its own purpose and open up challenges by civil liberties groups. The rules governing a UN list of al-Qaeda and Taliban suspects were recently changed because of legal challenges.

Can co-operation between national intelligence agencies be enhanced?

There is already considerable intelligence sharing between close allies such as the US and UK. But the prime purpose of each agency is the defence of its own country’s interests. In the latest case, Britain barred the Nigerian because he applied for a visa for a bogus college course rather than because he was thought to pose a terrorist threat to the UK.

Should US and other authorities tighten visa requirements?

Visa requirements are much tougher than before the September 11 2001 attacks. Citizens from countries such as the UK, who do not require a US visa, must now provide advance information on their travel plans. Others are issued visas by US embassies abroad administered by the state department. Incoming foreigners must give a full set of fingerprints and be photographed – but that is after their flight has landed.

What is the state of current technology?

In June the US House of Representatives voted for $15.7bn (€11bn, £9.9bn) funding for the Transportation Security Administration for 2010-2011. The TSA plans to push ahead with deployment of full body scanners, with the proviso that they are costly, still being tested and are intrusive – a “virtual strip search”, according to  privacy advocates.

The June bill also covers advanced self-defence training for flight crews and the deployment of sniffer dogs. A TSA public-private partnership to speed up security queues by creating special lanes for travellers willing to pay to have their biometric details on file hit a setback this year when the leading provider filed for bankruptcy.

Should the US and other countries adopt the Israeli model?

Israel has the tightest airline security on the world and El Al, the national carrier, boasts it is the world’s most secure airline. But the system involves intensive passenger profiling and intrusive questioning. Israeli authorities deny they use ethnic profiling, although anecdotal evidence is that security personnel are more alert to the potential threat from non-white and non-Jewish travellers.