A US drone strike on Thursday in Yemen\'s southeast province of Maarib has killed at least six suspected al Qaeda militants, officials have said. The attacks come after authorities announced they had foiled a plot to attack two major oil and gas export terminals and a provincial capital in the east of the country. On Wednesday, six militants were killed in two separate drone strikes in the eastern province of Shabwa.  A local security officer said senior al Qaeda members were not killed in the attack. Yemen’s security forces have been since been placed on high alert, amid fears of a possible al Qaeda retaliation. The US State department described the possible revenge strikes as an, \"immediate, specific threat.\"