( CNN ) -- The Malaysia Airlines mystery remains unresolved . While it is too early to speculate about the cause of the airliner 's disappearance , it is not a surprise that at least two people were able to board Malaysia Flight 370 with stolen passports . The fact is the world is far from having a foolproof system for checking travelers who move across borders . More than 50 % of transborder passenger movements take place at airports , but how passengers are treated in security lines at the world 's 600-plus major international airports is very much dependent on local regulations and practices . Various international organizations have proposed so-called `` smart '' solutions , such as biometric passports and electronic visas , but many forms of documentation used every day by millions of airline passengers are not digitized and are not being checked against any international databases . Moreover , without biometric protection , it is always possible to tamper with conventional passports , including the passport holder 's photograph , something that might have happened here . Of course , there are some important exceptions where tighter controls prevail . In the European Union , the nations that belong to the `` Schengen '' agreement , which abolished internal borders among 27 European countries , use a shared security database for travelers moving within the Schengen-area member states . The United States , the United Kingdom and the United Arab Emirates are the biggest users of the Interpol database for lost or stolen travel documents . Importantly , too , the United States requires airlines entering and leaving U.S. territory to submit travel document information about all passengers . Nevertheless , it remains true , even in a world that values security , that nations continue to have their own ideas about how to monitor travelers , how security information should be shared and to what extent identity information should be the subject of strong privacy protection . Most of the 190 nations that belong to Interpol , for example , simply do not bother to use the database even though they have access to it . As to privacy , even the United States and EU have different approaches , with the EU treating personal identity information as part of human and civil rights , while the U.S. authorities seem to have taken the view that individual privacy is almost always subject to national security concerns . Diversity among nations ' practices , therefore , can produce situations where travel document problems are missed or overlooked . Malaysia is far from being the only country where the passports of outgoing passengers are not typically checked . While we do not yet know the exact sequence of events , it is possible that China would have checked the stolen passports had it been required to issue visas . But no visas were required because the tickets were for continuing travel to Amsterdam , Netherlands . It is possible , though not of course yet certain , that existing procedures meant that Malaysia in effect passed responsibility to China and that China deferred to the Netherlands . Thus , all three nations probably complied with their own procedures and were not in violation of any international law or practice . The lack of alignment among these various nations ' procedures , however , meant that the passengers could use stolen travel documents to proceed through several security lines . The lessons from all of these national variations are clear : First , nations that develop their own security databases should still cross-check them with existing international systems such as Interpol . And second , the time has come for global coordination and standardized procedures for processing travel documentation : that includes not only widespread adoption of biometric travel documents , but also better coordination among nations as to where responsibility lies for checking documents that travelers use to identify themselves . The opinions expressed in this commentary are solely those of Brian Havel .
. Putin : It 's not surprising that at least two on the flight had stolen documents . He says how passengers treated on international lines varies with nations ' regulations . He says many Interpol member states do n't use database -- even though , EU differ on it . Havel : It 's time for global coordination , standardization for processing travel documents .