The United Nations Security Council has imposed sanctions on Eritrea for allegedly arming Somali insurgents and refusing to settle a border dispute with Djibouti.
The 15-member Council voted Wednesday to ban weapons sales to and from Eritrea. The resolution also places travel bans and asset freezes on individuals and companies to be named.
Eritrea's political and military leaders are expected to be among those affected.
The vote on the resolution was 13-to-one, with Libya voting against the sanctions and China, which has veto power, abstaining.
The United States and African Union have said that Eritrea supplies weapons to al-Shabab rebels trying to overthrow the Somali government.
Eritrean leaders have repeatedly denied the allegations, and had called on the Security Council to reject the sanctions.
In a letter to the Council last week, Asmara also said the sanctions might encourage Eritrea's rival Ethiopia to, in the letter's words, contemplate reckless military adventures. Eritrea and Ethiopia fought a border war from 1998 to 2000.
Wednesday's resolution was drafted by Uganda, whose troops make up the bulk of the African Union peacekeeping force in Somalia.
The resolution demands that Eritrea "cease arming, training, and equipping armed groups and their members, including al-Shabab" that seek to destabilize the Horn of Africa region.
It also demands that Eritrea resolve a border dispute with Djibouti. The two countries clashed along the border in June 2008, leaving a number of Djibouti's soldiers dead or missing.
The Security Council has already urged the countries to withdraw their forces from the disputed area. Djibouti has done so, while Eritrea has not.