ADDIS ABABA, ETHIOPIA — Ethiopian forces entered archrival Eritrea on Thursday and carried out what a government spokesman described as "a successful attack" against military posts.
Spokesman Shimeles Kemal said Ethiopia launched the attack because Eritrea was training "subversive groups" that carried out attacks inside Ethiopia.
Ethiopia and Eritrea fought a border war from 1998 to 2000. Tensions have reignited between the countries in recent months.
No details about the military operations or any damage or casualties were immediately released.
The "Eritrea government has continued launching attacks at Ethiopia through its proxy groups. The attacks had continued. And the recent attacks against European tourists is one of the reasons for the retaliation," Mr. Shimeles said.
Militants attacked European tourists from five nations traveling in Ethiopia's arid north in January. Five tourists were killed and two were kidnapped. The two kidnapped German tourists have since been released.
Ethiopia blamed gunmen from Eritrea for the attack.
The attacks Thursday by Ethiopian forces took place about 10 miles inside Eritrea's territory in areas called Gelakalay and Gimbina, Mr. Shimeles said. The Ethiopian forces have returned to Ethiopia, he said.
"Today's measures do not constitute a direct military confrontation between the two countries. The Ethiopian defense force has entered into Eritrea and launched a successful attack against military posts that have been used to organize, finance and train the subversive groups," Mr. Shimeles said.
Mr. Shimeles said it was unlikely that Eritrea would retaliate because it is "not in a position to launch a counterattack."
Eritrea's ambassador to the Addis Ababa-based African Union, Girma Asmerom, didn't immediately respond to phone calls seeking comment.
The border war between the two countries killed about 80,000 people. Recent signs have pointed to growing tension in the region.
Ethiopian Prime Minister Meles Zenawi told the country's parliament in April that his government would actively support Eritrean opposition groups to help topple that country's regime.
Ethiopia also blamed Eritrea for scheming bomb attacks on several targets in Addis Ababa during an African Union summit in January 2011.
Eritrea doesn't receive foreign aid and is sanctioned by the U.N. because of human rights violations. U.N. reports have indicated that Eritrea has supported Somalia's top militant group, the al Qaeda-linked al-Shabab. Eritrea has denied those accusations.