Tehran has been sending increasingly complex weapons to Yemen’s Houthi rebels even as Iranian officials have engaged in separate talks with the United States and Saudi Arabia about reducing tensions in the region, a top Pentagon official said Tuesday.

“In the Yemen context, we have seen more attacks from the Houthis launched at Saudi Arabia in the first half of this year than we have for several prior years,” Dana Stroul, the Pentagon’s top official for policy in the Middle East, told lawmakers on the Senate Foreign Relations Committee on Tuesday.

“Iran is increasing the lethality and complexity of both the equipment and the knowledge it transfers to the Houthis so that they can attack Saudi territory [and] Saudi civilians,” Stroul told lawmakers.

Yemen’s Houthi rebels, whom Western officials say have received support and training from Iran’s Islamic Revolutionary Guard Corps, have continued to launch ballistic missile and drone strikes into Saudi Arabia in recent years in response to the Riyadh-led military campaign in support of the Yemeni government. The technology also comes from Iran, American officials have said.