But the cross-border nature of the drug trade means countries have tried to reach basic agreement about what to ban.
The White House resisted efforts to portray a rift with the Pentagon, insisting it agreed with Thursday's comments by General Martin Dempsey, chairman of joint chiefs of staff, about the cross-border nature of the threat and claiming it was already responding by helping moderate Syrian rebels.
They are an unlikely pair faced with an unlikely crime – the body, when they come to move it, is revealed to be the torso of a Swedish politician paired with the legs of a Danish prostitute, reinforcing the investigation's cross-border nature.
And that does pose "additional challenges", due to the cross-border nature of these dealings, he adds.... (as flagged up earlier, analysts believe as much as half of Latvia's deposits come from outside the country) 12.31pm BST Finally, Rehn talks about the progress made by the Baltic states - remembering that he first visited Latvia 30 years ago.
But police forces are hampered by the difficulty of proving match-fixing and the cross-border nature of the scams: satellite broadcasting and online gambling have created lucrative and manipulable new betting markets, especially in South-East Asia, making the game a prime target for international crooks.
Nowhere is the cross-border nature of sectarian hostilities more clear than in Iraq's western desert, where Sunni Arabs are beginning to rally to the cause of the Syrian opposition and, in the process, perhaps strengthen their hand in dealings with an antagonistic Shiite-led national government in Baghdad.
Founded in the mid-1980s inside Texas prisons, the Barrio Aztecas have morphed into a prime example of the cross-border nature of Mexico's drug war, in which guns and money flow south and drugs flow north in a sinister trade that costs thousands of lives, far more of them Mexican than American.
One thing is increasingly clear when looking at the tangled web where politics and social media collide (with mass opinion manipulation the intended outcome): The interconnected, cross-border nature of the Internet, when meshed with well-funded digital political campaigning — and indeed buckets of personal data, is now placing huge strain on traditional legal structures at the nation-state level.
Two specialised UN agencies, ICAO for aviation and IMO for shipping, were charged with limiting and reducing emissions from these sectors 18 years ago since countries used the cross-border nature of these operations to side step including them in their own emissions accounting.
But the cross-border nature of commerce and thus infections also requires an effective international response.
