First, federal officials can renew their efforts to monitor and investigate domestic terrorism. Saturday’s attack came just a few weeks after reports emerged that the Department of Homeland Security had disbanded its group of analysts who focused on stopping such attacks. That occurred even though domestic terrorism is arguably one of the biggest threats to American national security: In 2017, 150 Americans were arrested for plotting attacks in the United States, compared to 110 arrests of international suspects.

That commitment requires action by the Trump administration — which seems uninterested in this growing threat. “Government can play a key role in preventing violent extremism. But we need resources and coordination to undermine extremism,” George Selim, a former Homeland Security official, wrote recently. The problem? “DHS is not only failing to increase resources to deal with new threats, it is also eliminating both staffing and millions of dollars in grants and programmatic support,” Selim wrote.

The Trump administration probably stands in the way of a second obvious path to combating extremists: cracking down on easy access to the types of guns that mass shooters favor. The shooter in Saturday’s attack reportedly used an “AR-type assault weapon” — obviously intending a high body count. That news is depressingly familiar to anyone who has followed mass shootings in the United States in recent years: AR-15-style rifles were used in the massacres at Las Vegas, Parkland, Orlando, and Newtown.