The UN Security Council announced new sanctions on Tuesday against three Houthi leaders for threatening the peace, security and stability of Yemen. The sanctions subject them to a global asset freeze, a travel ban and an arms embargo.

The three leaders sanctioned are Yusuf Al-Madani, Saleh Mesfer Saleh Al Shaer, and Muhammad Abd Al-Karim Al-Ghamari. The Houthi leaders are accused of coordinating attacks that impact civilians and civilian infrastructure. The sanctions follow Houthi attacks against the last government-controlled city in Yemen, Marib. Marib is a government stronghold; the Houthi regime controls the majority of the country, including Yemen’s capital, which the Houthis have controlled since 2015.

UN Security Council sanctions are authorized under Resolution 2140, which was passed in 2014. Resolution 2140 condemned Houthi attacks and designated a number of other leaders for sanctions. The UK proposed the most recent round of sanctions, authorized by Resolution 2140.

National sanctions are typically implemented by executives and enforced by agencies, such as the US Treasury’s Office of Foreign Assets Control (OFAC). National sanctions are enforceable because national governments control their borders and can direct local financial institutions to freeze designated persons’ assets. UN sanctions, however, are enforced differently. UN sanctions are overseen by sanctions committees consisting of all 15 members of the Security Council, but they rely on national enforcement. For example, the UK Office of Financial Sanctions Implementation (OFSI) operates off a consolidated list of UK, EU, and UN sanctions. The OFAC has not yet implemented the newest round of UN Yemen sanctions.