Opinion: Treat white supremacism as a global killer.

Ideology is not constrained by geography, especially in the Internet age, so it is unsurprising that white nationalism is less national than the name suggests. Notions of ethno-supremacy have always had their roots in transnational traditions of racism, and now online communities allow for actors in any state to draw inspiration from those in another. The Christchurch massacre is a case in point: allegedly carried out by an Australian, in New Zealand, in the image of a Norwegian and an American.

The shooting revealed serious shortcomings in how governments confront right-wing radicalism.

In the United States, Islamist extremism, even when it is homegrown, is considered international terrorism — and law enforcement treats it that way.

Right-wing radicalism, on the other hand, is called domestic terrorism if it is called terrorism at all. Sometimes, crimes motivated by the same set of values are classified as hate crimes or gang violence instead. Rightwing radicalism kills more Americans than Islamist extremism, and government should pursue the threat with more vigor. Doing so will require grappling with its domestic and global dimensions alike.

The first step to fighting white-supremacist extremism is to understand it, but that’s not possible now, because the Justice Department does not reliably collect the relevant information. Even hate-crime reporting is voluntary — and undercounted. A requirement for annual reports on all prosecutions of domestic terrorism and hate crimes, with relevant details, would go a long way toward assessing the problem. From there, the government should reallocate resources, which today are devoted disproportionately to fighting Islamist terrorism even as right-wing attacks rise. President Donald Trump pushed in the wrong direction when he shut down an interagency task force on countering violent extremism and ended relevant grants.

Just as tackling right-wing extremism domestically will require federal, state and local government agencies to coordinate, authorities confronting white supremacy’s global reach will need global partners.

The United States and its closest allies share classified intelligence about al-Qaida and the Islamic State. They should do the same regarding right-wing extremism, identifying links between terrorist networks, as well as information on how and where people are getting radicalized and who is radicalizing them. Sometimes, this will require sharing specific information about individuals or threats. Though white nationalism is not strictly national, many groups are centered in the United States, forcing authorities into a constitutional balancing act.

Law enforcement will have to distinguish between legal, if abhorrent, speech and violence or incitement to violence.

Internationally, too, governments must take care not to impinge on legitimate organizing even as they investigate terrorist communication across borders — which will present a particular challenge where prominent political parties have nationalist leanings themselves.

These are difficult lines to draw. But knowing where to draw them will first require treating white supremacism as the worldwide killer it is.