Iran summoned Russia’s charge d’affaires after Moscow and Arab countries released a joint statement earlier this week challenging Iran’s claim to disputed islands in the Persian Gulf, state media reported Sunday.

Iran’s official IRNA news agency said the Russian envoy was summoned on Saturday and handed a note to deliver to Moscow in which Tehran protested the statement the 6th Arab-Russian Cooperation Forum issued in Morocco that called for a peaceful solution to resolve the conflict between Iran and the United Arab Emirates over the islands.

Earlier on Saturday, Iran’s foreign minister Hossein Amirabdollahian told his Russian counterpart over the phone that “respecting countries’ sovereignty and integrity is among basic principles in the ties between nations,” IRNA said in a separate report.

This marked the second time this year that Iran has called for a Russian envoy in protest over comments on the disputed islands. Tehran summoned the Russian ambassador in July over a similar statement.

The diplomatic spat is a rare occurrence between the two countries that have deepened their ties since Moscow invaded Ukraine, with Iran supplying Russia with killer drones that have been used to devastating effect there. Both countries have also been strong backers of President Bashar Assad in Syria’s civil war.

In 2022, Iran summoned China’s envoy over a similar joint statement with Arab nations.

Iran took control of the three islands of Abu Musa, the Greater Tunb and the Lesser Tunb after British forces withdrew in 1971. It considers them an “inseparable” part of its territory. The UAE also claims the three islands and has long pressed for a negotiated solution.

The three islands dominate the approach to the strategic Strait of Hormuz, a key waterway through which about one-fifth of the world’s oil supply passes.

Iran says the islands have been part of Persian states from antiquity up until they were occupied by the British in the early 20th century. It also says an agreement reached with Sharjah, one of the UAE’s seven emirates, gives it the right to administer Abu Musa and station troops there.

There is no such agreement on the other two islands. The UAE says they belonged to the emirate of Ras al-Khaimah until Iran seized them by force days before the Emirati federation was formed.