YEREVAN (Azatutyun.am)—Russia will take steps to ensure its national security if Turkey opens a military base in Azerbaijan, the Kremlin said on Friday.

Turkish President Recep Tayyip Erdogan did not rule out Turkey’s permanent military presence in Azerbaijan after visiting on Tuesday the Nagorno-Karabakh town of Shushi (Shusha) captured by Azerbaijani forces during last year’s war.

In a joint declaration signed there, Erdogan and his Azerbaijani counterpart Ilham Aliyev pledged to further deepen military and other ties between their nations. Aliyev said the declaration calls for their “mutual military assistance” in the event of an armed conflict with third states.

Erdogan on Thursday did not exclude a Turkish military base in Azerbaijan. “There may be development, expansion here later,” he told Turkey’s NTV channel.

Commenting on Erdogan’s statement, Kremlin spokesman Dmitry Peskov said: “The deployment of military infrastructure by the [NATO] alliance countries near our borders is cause for our special attention as well as a reason for us to take steps to ensure our security and interests.”

Peskov also said Russia is “in close contact” with Turkey, Azerbaijan and Armenia on “further stabilizing the situation” in the South Caucasus after the Armenian-Azerbaijani war stopped by a Russian-brokered ceasefire in November. Regional players must not take actions containing “any elements that could cause a rise in tensions,” Russian news agencies quoted him as saying.

Russian Foreign Minister Sergei Lavrov was more dismissive of the talk of Turkish military presence in Azerbaijan. “We have not discussed that issue and do not comment on rumors,” he told a news conference on Friday.

Lavrov’s remarks contrasted with concerns voiced by some Russian lawmakers and pundits. Gazeta.ru, a major Russian news website, said Moscow’s reaction to a possible Turkish military deployment in Azerbaijan would be “very negative.”

It quoted Alexander Sherin, the deputy chairman of a Russian parliament committee on defense, as saying that Azerbaijan can already be considered a de facto NATO member because its soldiers fought alongside Turkish troops against Russia’s ally Armenia during the Karabakh war. “Its de jure membership [in NATO] is only a matter of time,” claimed Sherin.

The Armenian Foreign Ministry has condemned Aliyev’s and Erdogan’s visit to Shushi as a “provocation against regional peace and security.”

In a statement released on Thursday, the ministry accused Turkey and Azerbaijan of threatening Armenia’s territorial integrity after their “joint aggression” against Karabakh. It pointed to the Shushi declaration’s references to a “corridor” that should connect the Nakhichevan exclave with the rest of Azerbaijan via Armenia’s Syunik province.

Ankara lent Baku strong military and diplomatic support during the six-week Karabakh war. Yerevan says that Turkish military personnel participated in the hostilities on the Azerbaijani side along with thousands of mercenaries recruited in Syria’s Turkish-controlled northern regions.

The truce accord led to the deployment of 2,000 Russian peacekeeping soldiers in Karabakh. Russia has also deployed soldiers along some sections of Armenia’s border with Azerbaijan.