The military official, quoted anonymously, told CNN at least seven air force bombers were sent to Nehm province, northeast of the capital Sanaa, where the tribes had captured two bases from Saleh's Republican Guard.
"The guards attacked one of our villages for no reason," said Moqbel Najeeb, a local sheik. "We will not accept that and will fight back against anyone who tries to attack us."
Seven soldiers and five tribesmen were reported killed.
Meanwhile, fighting in the capital abated Friday as Saleh's emissaries negotiated with the Ahmar family, which has led the Hashid tribal confederation into joining the opposition. Saleh called off his weekly Friday rally and opposition protests diminished, The New York Times reported.
Sadiq al-Ahmar, the eldest of 10 brothers, spoke at an opposition rally Friday and confirmed the talks.
"We wanted our revolution to be peaceful but were forced to use the weapons," he said. "Now we would say we are ready for anything, peaceful or not peaceful."
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