KEY POINTS

  • Second incident to be reported within a week
  • U.S. Navy said the vessels were unmanned and unarmed
  • Tensions between the two countries have been high since 2018

The Iranian navy seized and later released two American surface drones in the Red Sea on Thursday, accusing it of blocking international waters and endangering maritime safety. It is the second such incident reported within a week, and comes in the backdrop of tensions between the two countries due to stalled nuclear deal negotiations.

According to Iranian state television, the two unmanned vessels were seized on Thursday and released in a safe area later.

"The [Iranian navy] frigate Jamaran seized the two vessels on Thursday to prevent any possible accident after issuing warnings to the US fleet. After international shipping lanes were secured, the two vessels were released in a safe area," Al Jazeera reported the state TV as saying Friday.

In a statement regarding the Thursday incident, the U.S. Navy said the two vessels were operated by the U.S 5th Fleet in the Red Sea. The Navy said the two Saildrone Explorers were unmanned and unarmed surface vessels operating in international waters without posing any risk to sea traffic.

"The unmanned surface vessels were unarmed and taking unclassified photos of the surrounding environment while loitering in an assigned patrol area at least four nautical miles from the nearest maritime traffic lane," the Navy's statement said.

"The vessels posed no risk to naval traffic and had been operating in the general vicinity of the Southern Red Sea for more than 200 consecutive days without incident," the statement added.

A similar incident was reported Tuesday, when personnel of Iran's Islamic Revolutionary Guard Corps (IRGC), seized an American sea drone in the Gulf and tried to tow it away. The vessel was released only when a U.S. Navy warship and helicopter approached. Tuesday's incident marks the first time the Navy's Middle East-based 5th Fleet's new drone task force has been targeted by Iran.

Iran has been building up its naval presence in the Red Sea, near the coast of Yemen where Tehran backs the Houthi Movement and also repeatedly warned the U.S. about its military activities in the Gulf.

The tension between the two countries is high since 2018 when then President Donald Trump withdrew from the landmark nuclear deal, which would have ensured the lifting of sanctions on Tehran in exchange for limits on its uranium enrichment. Efforts to revive the deal since remain stalled. The U.S. military had also recently launched retaliatory strikes on Iran-backed forces in Syria.

A US Navy Saildrone Explorer unmanned surface vessel (USV) or naval drone in the Arabian Gulf off Bahrain’s coast.