A group of Democrats on Friday urged the Biden administration to do more to confront the growing use of cryptocurrency markets in ransomware attacks, which have become an increasing national security threat over the past year.

Sens. Ed Markey (D-Mass.), Sheldon Whitehouse (D-R.I.), and Reps. Jim Langevin (D-R.I.) and Ted Lieu (D-Calif.) sent a letter to the leaders of the Homeland Security, Justice, State and Treasury departments on Friday asking them to pursue “stronger coordination” between the agencies on the issue of cryptocurrency.

They pointed to a massive increase in ransomware attacks, with the FBI’s Internet Crime Complaint Center receiving reports of almost 2,500 ransomware attacks with losses over $29 million in 2020.

“The proliferation of cryptocurrency has facilitated this explosive growth in ransomware attacks, largely by offering easy, fast, and difficult to trace methods for laundering illicit gains,” the lawmakers wrote. “We believe that increasing enforcement of existing money laundering and financial crimes statutes would play an important role in deterring ransomware attacks and facilitating the recovery of cryptocurrency paid to ransomware attackers.”