Yemen’s Houthi rebels announced on Monday the arrest of members of an alleged “American-Israeli spy network.” This comes just days after detaining at least 11 individuals, including those from aid organizations.

Maj. Gen. Abdulhakim al-Khayewani, head of the Houthis’ intelligence agency, declared the arrests, stating that the spy network initially operated from the U.S. Embassy in Sanaa. Following the closure of the embassy in 2015 due to the Houthi takeover of the capital Sanaa and northern Yemen, they continued “their subversive agenda under the cover of international and UN organizations,” he asserted.

He did not specify the exact number of individuals apprehended. Houthi authorities released what they claimed were videotaped confessions from 10 Yemenis, several of whom admitted to being recruited by the U.S. Embassy. These confessions did not include any of the U.N. employees who were arrested. The veracity of the Houthis’ claims could not be independently verified.

The United Nations announced on Friday the arrests of 11 Yemeni staff members. Six worked for the U.N.’s human rights agency, while others were employed by the special envoy’s office, its development arm, UNICEF, the World Food Program, and UNESCO. Additional aid groups also reported employee detentions, though the total number remains unknown.

These detentions coincide with heightened tensions as the Houthis, engaged in a war since their takeover of the north, have targeted shipping throughout the Red Sea corridor in response to the recent conflict in the Gaza Strip. Meanwhile, their administration has encountered increasing financial pressure, and the group has cracked down on dissent at home, including a recent sentence of death for 44 individuals.

Al-Khayewani depicted the spy network as having operated for decades to infiltrate Yemen’s economy, agriculture, health system, and other sectors with the intention of undermining them.

The war in Yemen has resulted in the deaths of over 150,000 individuals, including both fighters and civilians, creating one of the world’s worst humanitarian disasters, which has claimed the lives of tens of thousands more. The Houthis’ attacks on shipping have served to distract from their internal challenges and the stalled war. However, they have faced escalating casualties and damage from U.S.-led airstrikes targeting the group for months.

The specific reason behind the recent detentions remains unclear. Former employees of the U.S. Embassy in Sanaa, which closed in 2015, have previously been detained and held by the Houthis.

This development comes at a time when the Houthis have encountered difficulties securing sufficient currency to sustain the economy in areas under their control. Yemen’s exiled government in the southern city of Aden has demanded that all banks relocate their headquarters to Aden as a measure to curb the drastic decline in the value of the currency and regain control over the economy.