Azerbaijan began joint military exercises with Turkey on Tuesday, a week after Iran held its own border exercises and accused the Azeris of joining Israel’s “Zionist regime.” Azerbaijan also pushed back by shuttering a mosque linked to Iranian Supreme Leader Ayatollah Ali Khamenei.

Radio Free Europe (RFE) summarized the deteriorating relationship between the governments in Tehran and Baku on Wednesday:

Azerbaijan and Iran have long been at loggerheads over Tehran’s backing of Armenia, but normally friendly relations began to deteriorate following joint military drills that Azerbaijani troops conducted alongside their Turkish and Pakistani counterparts last month.

Azerbaijan’s restrictions on Iranian truck drivers’ access to Armenia and the detention of two drivers, as well as Azerbaijan’s ties to Iran’s archenemy Israel are also fueling a spiraling standoff between the two neighbors.

NATO member Turkey threw its weight behind Azerbaijan in its victory against ethnic Armenian forces in a six-week war last fall over the breakaway region of Nagorno-Karabakh. The war ended following a Russian-brokered cease-fire agreement reached on November 9.

https://twitter.com/RFERL/status/1445597691317161988

According to the Turkish Defense Ministry, the “Unshakable Brotherhood” joint exercise will include everything from mechanized infantry to drones. The nominal purpose of the exercise is to “develop friendship, cooperation, and coordination between the Turkish and Azerbaijani land forces, and share knowledge and experience to improve interoperability.”

Turkey also seems interested in sending signals to Armenia, whose forces have scuffled along the border a few times since the conclusion of the Nagorno-Karabakh war, with some injuries and fatalities. Armenia accuses Azeri forces of provoking these confrontations, and vice versa.

Turkish President Recep Tayyip Erdogan listens to Russian President Vladimir Putin during their meeting in the Bocharov Ruchei residence in the Black Sea resort of Sochi, Russia, Wednesday, Sept. 29, 2021. (Vladimir Smirnov, Sputnik, Kremlin Pool Photo via AP)

On Tuesday, Azerbaijan irked Iran by shuttering the Husseiniyya Mosque in Baku, which is linked to Iran’s Ayatollah Khamenei, and also closing the office of Khamenei’s representative Ali Akbar Ojaghnejad, which is located on the mosque grounds. Ojaghnejad has been posted in Azerbaijan since 1996.

The Azeri Interior Ministry claimed the mosque is “one of the places where the coronavirus has been spreading in recent days” and said it was shut down while “appropriate measures are being taken by the epidemiological service.”

The Iranian embassy in Baku complained it was given no advance notice that the mosque and Ojaghnejad’s office would be closed, and said it would pursue the matter through “diplomatic channels.”

The Iranian Foreign Ministry on Monday warned Azerbaijan to stop allowing “third parties” to use its “borders and territories,” contemptuously addressing the Azerbaijan government as though it were a sock puppet manipulated by Israel.

Azerbaijan’s relations with Russia have also soured since the Russians helped broker the cease-fire in Nagorno-Karabakh. Baku is irked that Moscow has not supported its claims to the disputed region more strongly, and blames Russian peacekeepers for not doing enough to keep Armenian fighters from entering areas claimed by Azerbaijan.