Russian strongman Vladimir Putin apologized to Azerbaijan on Saturday for the crash of a civilian flight carrying passengers from Baku to Grozny in Russia-controlled Chechnya.

Putin had a phone call with Azerbaijani president Ilham Aliyev and “apologised for the tragic incident that occurred in Russian airspace and once again expressed his deep and sincere condolences to the families of the victims and wished a speedy recovery to the injured,” the Kremlin said.

Azerbaijan’s president on Sunday demanded that Russia admit responsibility for the incident that led to the Christmas Day crash of a passenger plane that killed 38 people and pay compensation to the government and affected families.

Azerbaijan is proposing to sign a document with Armenia on the basic principles of a future peace treaty as an interim measure as they wrangle over a broader deal, a senior Azerbaijani official said on Sunday.

Both Armenia and Azerbaijan have repeatedly said they want to sign a peace treaty to end the conflict over the former breakaway Azerbaijani region of Nagorno-Karabakh.

Armenia's foreign minister will travel to Washington on July 9-10 during the NATO summit, his ministry said on Monday, as the country, once a top Russian ally, seeks to build closer ties with the West.

"Minister (Ararat) Mirzoyan will take part in an event with NATO partners on the sidelines of the NATO summit, as well as in other events dedicated to the 75th anniversary of the organisation. Bilateral meetings are also planned," a spokesperson for the ministry said on the Telegram messaging app.

Gunmen opened fire on places of worship in two cities of Russia’s southernmost Dagestan province on Sunday, killing at least 15 police officers and four civilians, including an Orthodox priest, in what appeared to be a coordinated attack.

Sergey Melikov, head of the Dagestan Republic, said at least six “militants” were also killed following the attacks on churches, synagogues and police posts in the cities of Derbent and the regional capital Makhachkala, which are about 120 kilometers (75 miles) apart.

Attacks on police posts, churches and a synagogue in Russia's North Caucasus republic of Dagestan have left 19 police officers and several civilians dead. Six gunmen were also killed.

At least sixteen people were taken to hospitals with injuries.

Three days of mourning have been declared in Dagestan, a predominantly Muslim republic in southern Russia which neighbours Chechnya.

The apparently coordinated attacks targeted the cities of Derbent and Makhachkala on the Orthodox festival of Pentecost, with an Orthodox priest among those killed.

Gunmen opened fire on two synagogues, two Orthodox churches and a police post in Russia's North Caucasus region of Dagestan on Sunday.

The Investigative Committee of the Russian Federation opened a terrorism investigation in response to the "armed attacks in Derbent and Makhachkala, as a result of which police officers and civilians were killed and injured," according to the agency’s Telegram page. 

Armenia declared Friday that it was recognizing Palestinian statehood, prompting Israel to summon the country’s ambassador for a dressing down.

The Armenian foreign ministry said in a statement that Yerevan supports a two-state solution to the conflict between Israel and the Palestinians and is “genuinely committed to establishing peace and stability in the Middle East and lasting reconciliation.”

Israel’s Foreign Ministry said that in response to the recognition, the ministry had summoned the Armenian ambassador, Arman Akopian, to be reprimanded.