A senior operative of the al-Qaeda network in Yemen the group that claimed responsibility for the failed Christmas Day attack on an American passenger jet over Detroit has threatened more attacks on the United States. The U.S. has become increasingly worried about militants based in Yemen since al-Qaeda groups there and in Saudi Arabia merged last year. The group has openly targeted U.S. and other Western interests in Yemen, and -- as demonstrated by the December 25 attack -- abroad. Qasim al-Raimi, a top military commander for al-Qaeda in the Arabian Peninsula, warned Americans in an article published in an online militant magazine that the group will blow up the earth from below your feet. You have attacked us in the midst of our household, so wait for what will attack you in the midst of yours, al-Raimi said, according to a translation of the message from the SITE Intelligence Group, which monitors militant Websites. Washington has pressured Yemens government to crack down on the al-Qaeda network, and the Pentagon has earmarked some $150 million in military assistance to Yemen to help combat the threat.