WASHINGTON — North Korea has vastly expanded its use of the internet in ways that enable its leader, Kim Jong-un, to evade a “maximum pressure” American sanctions campaign and turn to new forms of cybercrime to prop up his government, according to a new study.

The study concludes that since 2017 — the year President Trump threatened “fire and fury like the world has never seen” against the country — the North’s use of the internet has surged about 300 percent. Nearly half of that traffic now flows through a new connection in Russia, avoiding the North’s longtime dependency on a single digital pipeline through China.

The surge has a clear purpose, according to the report released Sunday by Recorded Future, a Cambridge, Mass., group known for its deep examinations of how nations use digital weaponry: circumventing financial pressure and sanctions by the West. Over the past three years, the study concluded, North Korea has improved its ability to both steal and “mine” cryptocurrencies, hide its footprints in gaining technology for its nuclear program and cyberoperations, and use the internet for day-to-day control of its government.

“What this tells you is that our entire concept of how to control the North’s financial engagement with the world is based on an image of the North that is fixed in the past,” said Priscilla Moriuchi, a former National Security Agency analyst who directed the study and has long focused on North Korea and Iran. “They have succeeded at an easy-to-replicate model of how to move large amounts of money around the world, and do it in a way our sanctions do not touch.”