An American MQ-9 Reaper flying near Yemen has been shot down by Houthi militants, a U.S. official confirmed to ABC News and the Pentagon later said on Tuesday.

       The Houthis said they had targeted the Reaper as well as two American ships in the Gulf of Aden in a statement Monday.

       A still image taken of video released by Houthis of what they say is the downing of a U.S. dro...Show more ---Show more

       Houthi Military Media via Reuters

       This is their second downing of a Reaper, having shot one down one in international airspace near Yemen in November.

       MORE: Unmanned Houthi submarines pose new threat to US warships in Red Sea

       The U.S. has designated the Houthis as a global terrorist organization amid rising regional tensions and a consistent deployment of missiles and drones against each other since war in Gaza broke out.

       An MQ-9 Reaper flies a training mission over the Nevada Test and Training Range, July 15, 2019.

       Airman 1st Class William Rio Rosado/U.S. Air Force

       MORE: US, UK launch large-scale retaliatory strikes against Iran-backed Houthi militants in Yemen

       The Pentagon says the drone, taken down by a surface-to-air missile, has not been recovered and that an investigation is ongoing.

       Pentagon Deputy Press Secretary Sabrina Singh conceded that Houthi "attacks are getting more sophisticated," but she insisted "our dynamic strikes or coalition strikes absolutely have an impact."

       Singh noted an "uptick" over the weekend of activity by the Houthis, who are backed by Iran.

       "If Iran does have a role to play with the Houthis, it's not doing it," she said, urging the Iranians to exert influence over the Houthis to tame tensions.

       The U.S. conducted what it calls five self-defense strikes Sunday against the Houthis, one of which targeted an unmanned underwater vessel, the first submarine the U.S. says the Houthis have employed since tensions began to flare in October.

       The Coast Guard reported an interdiction this month that seized the components of the underwater drone that U.S. forces targeted Sunday.

       The remotely-operated Reaper is charged primarily with intelligence gathering and costs more than $50 million, according to the Air Force.

       ABC News' Anne Flaherty and Will Gretsky contributed to this report.