Earlier this week, a group of global news organizations published stories based on millions of leaked documents from a Panamanian law firm that reveal how some of the world’s most wealthy and politically powerful people, from Vladimir Putin to Jackie Chan, used offshore bank accounts to hide their wealth and avoid taxes. These revelations have now become an issue in the Democratic primaries. Bernie Sanders and his allies are alleging that a free trade deal with Panama he opposed but Congress approved and Obama signed in 2011 is partly responsible for the Wild West financial shenanigans in that country. The Obama administration and its allies in Congress counter that Sanders couldn’t be more wrong because, as a condition of signing the trade pact, U.S. negotiators required Panama to sign a separate financial transparency treaty with the United State that they had hitherto resisted.

One important piece of evidence suggesting that the Sanders side may be wrong on this is that very few Americans seem to appear on the lists. Indeed, since the lists were revealed a number of follow up stories have appeared in the media attempting to explain this anomaly. One theory is that America states like Delaware provide sufficient pseudo tax havens so that the demand just isn’t there. Another is that more American names will be revealed as reporters dig further into the data. Yet another, offered by Megan McArdle at Bloomberg View, is that since most of names on the list are of people living in unstable kleptocracies the data dump is actually “not so much an indictment of global capitalism as an indictment of countries that have weak institutions and a lot of corruption.”

One person who knows this terrain is my friend William Wechsler. Will was the point person combating money laundering in the Clinton Treasury Department and later oversaw counternarcotics and special operations in the Obama Pentagon. He’s now a senior fellow at the Center of American Progress. I sent him an email soliciting his views. Here, with his permission, is what he wrote back:

1. There’s still a lot of time for American names to come out.

2. To the degree they don’t, one explanation is that U.S. regulations and law enforcement are among the strongest on these subjects. At the end of the Clinton Administration we put out an advisory on Panama specifically. It was withdrawn early in the Bush Administration after Panama passed a law. But it’s still been a good place for money launders — see last year’s State INCSR report on Panama here.

3. Another factor that is specific to Americans is that we have a relatively unusual tax system in that for U.S. citizens worldwide income is subject to U.S. income tax, regardless of where they reside. Every other developed country that I’m familiar with taxes their citizens only on income that they earn domestically. So if you want to evade taxes in these other countries you just have to have some way of showing that your income was earned abroad. But if you want to evade taxes in the U.S. you have to somehow show that you didn’t earn the money at all. Obviously, it’s much easier to do the former than the latter. Indeed, I suspect that activity constituted much of the work of this Panamanian law firm. If that’s the case then they really wouldn’t have been marketing much to Americans.

So, what the lack of many American names in the Panama Papers might mean–and it probably is too early to know for sure–is that the United States has this part of its financial house more in order than we might have feared. And it looks like more cleanup efforts are on the way. A few days ago, the Obama Treasury Department announced that it is on the verge of releasing new rules that will require banks, including foreign banks with U.S. branches, to find out the identities of the actual human beings who own shell companies. If done right–and if the next president doesn’t undue it–that rule could put a big crimp in the use of such shell companies by the rich to hide taxable income and criminals to cloak ill-gotten gains.