The total cost of the US military's operation against the Iran-backed Houthi militants in Yemen is nearing $1 billion in just under three weeks, even as the attacks have had limited impact on destroying the terror group's capabilities, three people briefed on the campaign's progress told CNN. The military offensive, which was launched on March 15, has already used hundreds of millions of dollars worth of munitions for strikes against the group, including JASSM long-range cruise missiles, JSOWs, which are GPS-guided glide bombs, and Tomahawk missiles, the sources said. B-2 bombers out of Diego Garcia are also being used against the Houthis, and an additional aircraft carrier as well as several fighter squadrons and air defense systems will soon be moved into the Central Command region, defense officials said this week.