THE 500-euro note is sometimes called the “Bin Laden”  after all, Europeans may never see the 500 euro, but they know it is out there somewhere. Unfortunately, Al Qaeda’s leader and the 500-euro bill are connected in another way: high-denomination bills make it a lot easier for terrorists to operate.

Organized crime has always been a cash industry. In 1969, the Treasury stopped issuing $500, $1,000, $5,000 and $10,000 bills specifically to impede crime syndicates  the only entities that were still using such large bills after the introduction of electronic money transfers.

Nowadays, terrorist networks have become important users of cash. No organization understands this better than the United States military. During the early years of coalition operations in Afghanistan and Iraq, American forces distributed cash liberally. From 2003 and 2008, about $19 billion in physical money was handed out to Iraqi suppliers and contractors.

But the military has gradually realized that the anonymity of cash makes it easy for terrorists and insurgents to smuggle in money and make purchases without a trace. That’s why for the past few years the military has been striving to replace its cash transactions with electronic fund transfers and debit card payments in the hopes of achieving a “cashless battlefield,” in the words of Peter Kunkel, a former assistant secretary of the Army.