Iran summoned Russia’s ambassador on Wednesday after Moscow released a joint statement with Arab countries earlier this week challenging Iran’s claim to disputed islands in the Persian Gulf.

It marked a rare spat between Iran and Russia, which have deepened ties since Moscow invaded Ukraine, with Iran supplying killer drones that have been used to devastating effect there. Iran and Russia are also strong backers of President Bashar al-Assad in Syria’s civil war.

Iran’s official IRNA news agency said the ambassador was summoned over a joint statement released Monday after a meeting in Moscow between Russia and the Gulf Cooperation Council, which includes the United Arab Emirates, Saudi Arabia, Kuwait, Qatar, Bahrain and Oman.

In the statement, the ministers affirmed their support for efforts “to reach a peaceful solution to the issue of the three islands, Greater Tunb, Lesser Tunb and Abu Musa, through bilateral negotiations or the International Court of Justice,” according to the Saudi Press Agency.

Iran took control the three islands after British forces withdrew in 1971 and considers them an “inseparable” part of its territory. The United Arab Emirates also claims the three islands and has long pressed for a negotiated solution.

“We never stand upon ceremony with any side over Iran’s independence, sovereignty and integrity,” Iran’s Foreign Minister Hossein Amirabdollahian tweeted, without naming Russia.

Iran summoned China’s envoy over similar remarks on the disputed islands in December.

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.