Iran has slammed a US blockade around its ports as a “grave violation” of its sovereignty, as Washington and Tehran’s belligerent rhetoric rattle a fragile truce, AFP reports.

“The imposition of a maritime blockade constitutes a grave violation of the sovereignty and territorial integrity of the Islamic Republic of Iran,” Iran’s ambassador to the United Nations Amir Saeid Iravani wrote to UN Secretary General Antonio Guterres, in a letter seen by AFP.

The “unlawful” blockade also “constitutes a serious violation of the fundamental principles of the international law of the sea,” Iravani added.