The Obama administration is sanctioning six people, including Eritrea's external intelligence chief and a senior Eritrean military officer, for their roles in allegedly supporting the Somali group al-Shabab.
The Treasury Department announced the sanctions on Thursday under an executive order that allows the administration to impose punitive measures on individuals who threaten "peace, security or stability" in Somalia.
The sanctions freeze any assets the men may have in the US, and block Americans from doing business with them.
The six are accused of providing financial and logistical support to al-Shabab, an armed Islamist group which is blamed for numerous attacks against African Union peacekeepers in Somalia, as well as attacks in Uganda and Kenya.
"The United States is determined to target those who are responsible for the ongoing bloodshed and instability in Somalia," said Adam Szubin, the director of the Treasury's Office of Foreign Assets Control, which administers the sanctions.
The two Eritreans hit by the sanctions are Colonel Tewolde Habte Negash, the country's external intelligence chief and the alleged architect of Eritrea's relationship with al-Shabab; and Colonel Taeme Abraham Goitom, who is said to be involved with organising armed opposition to the Somali government.
Eritrea has long been accused of fomenting violence in Somalia, in part to keep its archrival Ethiopia, which shares a long border with Somalia, concerned about unrest there.
The sanctions also apply to a Sudanese man accused of recruiting foreign fighters for al-Shabab and three Kenyans, including a cleric, who are said to have raised money and arms for the group.
The cleric, Aboud Rogo Mohammed, is accused of raising funds for al-Shabab and helping recruits get to Somalia to join the group. The other two Kenyans, Omar Awadh Omar and Abubaker Shariff Ahmed, are both imprisoned.
Omar is awaiting trial in Uganda for his alleged involvement in a July 2010 attack on restaurants showing World Cup football matches in Kampala that killed 74 people.
Ahmed was arrested in Kenya in 2010 on suspicion of involvement in the bombing of a bus terminal in Nairobi.