In June 1977, Carter relayed a secret message to Barre, reportedly telling him that whatever he did in the Ogaden was his own business, but if he dropped his claims to Kenya and Djibouti, Washington would sympathetically consider his "legitimate" defensive needs. A few days later, Carter told the Somali ambassador that although the United States couldn't at that time provide military aid, Washington would encourage its allies to help Somalia maintain its defensive strength. The next month, Carter approved in principle a decision to cooperate with other countries in arming Somalia, and on July 25 the Somali ambassador was notified that the United States would provide weapons. Not surprisingly, Barre took this as a green light to proceed with his invasion of the Ogaden.
When the Somalia invasion became evident to the outside world in August, the Carter administration decided that it would not provide arms to Mogadishu as long as Somali troops were in Ethiopia. Washington declared an
arms embargo on both sides, but still maneuvered for advantage on the Horn. On the one hand, U.S. officials, like Moscow, still considered Ethiopia the more valuable catch. So while they denounced the Kremlin for arming Ethiopia, they were silent about
Israeli arms support for Addis Ababa and indeed about U.S. deliveries of 23 trucks and $400,000 worth of nonlethal military spare parts to Ethiopia.
http://www.zmag.org/zmag/articles/shalomsomalia.html===========================================================================================
Interesting the last paragraph. While Carter reneged on his promise to supply Somalia arms and weapons, he also declared and enforced arms embargo on Somalia, was silent about Israel arming Ethiopia, and even sent 23 trucks and $400,000 worth of nonlethal military spare parts to Ethiopia.