From the Summary: "U.S. economic sanctions imposed on North Korea are instigated by that country's activities related to weapons proliferation, especially its tests since 2006 of nuclear weapons and missile technology; regional disruptions; international terrorism; narcotics trafficking; undemocratic governance; and illicit activities in international markets, including money laundering, counterfeiting of goods and currency, and bulk cash smuggling. [...] In addition to economic and diplomatic restrictions on the U.S.-North Korea bilateral relationship, other states' failure or resistance to comply with Security Council requirements, sanctions evasion, and transactions with persons and entities subject to U.S. sanctions as part of the United States' policy toward North Korea invites the United States to impose 'secondary sanctions'. Third parties--individuals, entities, or governments--may find their U.S.-based assets blocked, transactions and contracts with U.S. persons prohibited, use of the U.S. financial system denied, and U.S. support in the international financial institutions curtailed."
CRS Report for Congress, R41438
Congressional Research Service: https://crsreports.congress.gov/