When Ethiopian forces entered Somalia in December 2006 to support the embattled transitional government against the Islamic Courts Union, the incursion was only the latest event in a decades-long history of conflict between the two countries.

Although the recent strife was portrayed by some in the international community as one front in a global struggle against Islamic extremism, some experts say the key to comprehending the situation is to understand the historical relationships among Somalia and its neighbors, particularly Ethiopia and Eritrea.

"To imagine that the very dangerous situation in Somalia is primarily about al-Qaida is to misunderstand the predominantly local dynamics that drive the conflict," Terrence Lyons, an expert on the Horn of Africa at George Mason University, told the Voice of America in December.

Ethiopian-Somali wars
Ethiopia and Somalia fought their first war in 1964, only four years after Italian Somaliland and British Somaliland gained independence and merged to form the Somali Republic.

Most of the people who inhabit the Ogaden region in Ethiopia's southeast corner are ethnic Somalis who speak Somali, and Somalia has always maintained that the land there rightfully should be part of a greater Somalia.

This led to a border war in 1964, and then to the much bloodier Ogaden war from 1977 to 1978. At the time, Ethiopia seemed weakened after the overthrow of its longtime emperor, Haile Selassie. Somalia, trying to press this advantage, invaded in July 1977. But an infusion of troops and aid from Cuba and the Soviet Union allowed Ethiopia to defeat Somalia.

"Ethiopia views itself as having had to push back against an expansionist Somalia movement at least three times," said Akwe Amosu, a senior policy analyst for Africa at the Open Society Institute in Washington. "And that means that there is a high level of sensitivity."

In recent years, Amosu said, that sensitivity has been particularly high because of Ethiopia's own complicated internal politics. Prime Minister Meles Zenawi's government, which is mainly drawn from the Tigrayan people from Ethiopia's north, is unpopular with many of the other ethnic groups that make up the diverse country. "Those groups are seen as susceptible to organizing," Amosu said.

Ethiopia's government has also kept a close eye on -- and often a hand in -- the tumultuous situation in Somalia over the past 15 years. Since 1991, Somalia has not had a stable, effective government.

"Many attempts to set up a Somali central government during the '90s ran afoul of Ethiopian opposition, because they wanted their security guaranteed," said Alex De Waal, an expert on Africa at the Global Equity Initiative at Harvard University.

Longtime Ethiopian ally Abdullahi Yusuf Ahmed became the president of Somalia's current government, the Transitional Federal Government, which formed in 2004 with Ethiopia's approval.

The TFG's close relationship with Ethiopia added to the government's struggle to gain acceptance from the people of Somalia. The ties with the transitional government meant Ethiopia had a vested interest in keeping the Islamic Courts Union from taking power.

Eritrean involvement
Ethiopia's tumultuous relationship with its tiny neighbor Eritrea also figures heavily into rifts in the region.

"Historically, the Eritreans have made common cause with the Somalis against the central Ethiopian government," said De Waal.

In fact, some experts say that a main cause of Ethiopia's decision to enter Somalia in December 2006 may have been the country's desire to make a show of force for Eritrea's benefit.

Eritrea, which was once a province of Ethiopia, gained its independence in 1991 after a 30-year struggle. But the relationship between the two countries has continued to be fractious, and they fought a border war from 1998 until 2000 that resulted in more than 100,000 casualties on the two sides.

Although the war ended with a negotiated agreement on ownership of the disputed area, neither government has ever fully accepted or implemented the agreement. Both have periodically remobilized troops along the border, and tensions between the two countries remain high.

The United Nations and other groups have accused Eritrea of providing arms and other support to the Islamic Courts Union -- under the logic of "the enemy of my enemy is my friend" -- in an effort to destabilize Ethiopia. A November 2006 U.N. report concluded that at least 2000 Eritrean troops were in Somalia supporting the Islamic Courts Union, a charge that Eritrea denies.

Eritrea continues to condemn Ethiopia's intervention in Somalia, but concerns that the armed conflict in Somalia could spark widespread warfare in the region have not come to fruition.

"The thing that makes Somalia particularly explosive is the links between Ethiopia and Eritrea and the Ethiopian-Eritrean conflict that is being played out by proxy in Somalia," George Mason University's Lyons told Voice of America.

However, the conflict in the Horn of Africa is not the struggle between Islamic Somalia and non-Islamic Ethiopia that some might take it to be.

"Ethiopia is a secular country with a secular government," De Waal said. "In fact the chief of staff of the Ethiopian army, the person who invaded Somalia, is himself a Muslim."

The population of Ethiopia is about evenly split between Christian and Muslim. The same is true for Eritrea, despite its support for the Islamic Courts Union.

"Really what you're looking at here is not religious identity, but politics," Amosu said.

-- By Lea Winerman, Online NewsHour