The UN Security Council has "strongly condemned" the violence between Azerbaijani and Armenian forces along the Line Of Contact after three days of fighting this week over the breakaway Azerbaijani region of Nagorno-Karabakh.
After a closed-door meeting, the council reiterated UN Secretary-General Antonio Guterres's appeal for both sides to "immediately stop fighting, de-escalate tensions, and return to meaningful negotiations without delay."
However, intense fighting "along the entire front line" spilled over into its fourth day on September 30. In fact, the violence and tensions escalated as two Armenian warplanes were said to have been downed or crashed, while Ankara pledged to "do what is necessary" to back ally Azerbaijan.
Outside powers have been left scrambling. France blamed Azerbaijani forces for sparking the latest violence and accused Ankara of "bellicose" language in its support of Baku. And the European Court of Human Rights demanded that both sides avoid military actions that threaten civilians.
While the fighting threatens to be more widespread and deadlier than previous breakdowns since the shaky cease-fire reached 26 years ago, it did not come out of the blue.
There were mounting signals in recent days and weeks of intense frustration on both sides of Europe's longest "frozen conflict," and statements and actions leading up to this week's bloodshed pointed to the potential for a major escalation.
OSCE Failures At Mediation
Russia, France, and the United States have spearheaded mediated peace efforts within the Organization for Security and Cooperation in Europe's Minsk Group to find a peaceful solution to the Nagorno-Karabakh conflict.
But the Minsk Group's last significant effort to achieve peace between Armenia and Azerbaijan fell apart in 2010.
Critics say it has slid into an inactive and ineffectual peace process that has arguably been marked by inattention from international actors.
"A lot of time has been wasted," Thomas deWaal, a senior fellow with Carnegie Europe specializing in Eastern Europe and the Caucasus region, said recently. "The last time serious talks were 20 years ago. Instead there has been sporadic contact and what one mediator calls 'Kabuki negotiations.'"
July Flare-Up, Nationalist Anger
The most conspicuous sign of trouble came in July with cross-border shelling and other fighting in a northern region along the Armenian-Azerbaijani border. Unusually, it was confined to an area on Azerbaijan and Armenia's internationally recognized border.
Most of the frequent skirmishes of the past decade have taken place along the so-called Line of Contact separating Azerbaijani and ethnic Armenian forces in and around the disputed territory.
But it was the deadliest violence since 2016, and included heavy artillery, tank fire, and aerial attacks.
Russia helped negotiate a quick cease-fire to put an end to the July fighting.
Chants of "Return Karabakh!" and "Revenge!" arose from angry crowds in the streets of Baku. Orchestrated or not, the nationalist foment in Azerbaijan's capital was reminiscent of scenes during the 2016 flare-up, when the Azerbaijani authorities reported turning away thousands of volunteers eager to fight for Nagorno-Karabakh and the country.
The Azerbaijani side had made limited territorial gains in the 2016 fighting, the first time that had happened in more than two decades. Chatham House’s Laurence Broers said at the time that Azerbaijani media framed it as "a turning of the tide."
"I'm sure that there is pressure in Azerbaijan to sustain the narrative of military success," he told Armenian media this week.
Joint Military Exercises, Tensions
Within weeks of the eruption of violence in mid-July, joint military exercises were under way with outside regional powers in both countries to combat precisely the kind of threats that have manifested themselves this week.
Armenia announced on July 23 that its troops were training with Russian air-defense commanders and troops to improve responses to possible threats from unmanned aerial vehicles. By all accounts, such aircraft have played a conspicuous role in the current conflict.
On the other side of the border, Azerbaijan conducted nearly two weeks of joint military exercises alongside Turkish troops. They included air and air-defense forces as well as armored vehicles and heavy artillery. The Jamestown Foundation's Vasif Huseynov called them "the largest of its [sic] kind in the recent history of military cooperation between the two countries."
Armenian Defense Minister David Tonoyan called the Turkish-Azerbaijani drills "destabilizing."
Aliyev's Challenge To Moscow
Moscow, a traditional Armenian ally, has sought to exert greater influence in Yerevan since Armenia's bloodless "revolution" two years ago.
Armenia hosts a Russian military base near Gyumri in northwestern Armenia near the Turkish and Georgian borders. It is also a member of the Russia-led Collective Security Treaty Organization (CSTO) and the Eurasian Economic Union (EEU).
Armenia also enjoys Russian security guarantees.
But recent cargo shipments to Armenia after the July violence piqued Aliyev's public anger.
In August, the Azerbaijani president was said to have asked Russian President Vladimir Putin about reports of large shipments of military supplies that began on or around July 17.
The reports have not been confirmed.
But Aliyev reportedly suggested there had been an acceleration of such supplies -- some 400 tons since the July fighting -- and he said they "caused concern and serious questions in Azerbaijani society," according to his press service. He argued that Armenia had intended to draw "third parties" into the conflict and asked Putin to clarify the situation.
Pashinian Changes Tone In Stepanakert
Armenian Prime Minister Nikol Pashinian took a more defiant tone with respect to Nagorno-Karabakh during a visit to the region in early August.
"Artsakh is Armenia, and that's it," he told a crowd of ethnic Armenians in the de facto capital, Stepanakert, invoking the name for Nagorno-Karabakh that Armenians chose in a 2017 referendum that is not recognized by the international community.
It appeared to signal a pivot by Pashinian from an arm's length relationship with the territory to an embrace of a region whose leadership had deep ties to the very officials that Pashinian's bloodless revolution had unseated two years before.
It also vastly overstepped lines contained in the 1994 cease-fire that is the starting point for talks within the OSCE Minsk Group format.
The speech immediately evoked anger in Azerbaijan, and was described by a media outlet with purported ties to Azerbaijan's security services as a more "radical and intransigent" position.
Then, in the middle of September, the de facto leader of Nagorno-Karabakh, Arayik Aratiunian, pledged to move the seat of the occupied territory's government from Stepanakert to Shusha, a Soviet-era mountain resort that was a stronghold of Armenian life in medieval times.
At the UN General Assembly last week, Turkish President Recep Tayyip Erdogan accused Armenia of being "the biggest obstacle to lasting peace and stability in the South Caucasus."
He said its lingering conflict with Turkish ally Azerbaijan over Nagorno-Karabakh should be resolved in line with Azerbaijan's territorial integrity and sovereignty.
AFP this week quoted Jean Radvanyi, an academic specializing in post-Soviet geopolitics, as saying Turkey's support for Baku fit into a nationalism-fueled "historic project" to create a union of Turkic peoples. "It's also a way to show Turkey is a growing regional power that is capable of intervening in many theaters of war," he said.
"What we're seeing, effectively, is perhaps the movement of the resolution process, the settlement process, out of a Euro-Atlantic framework and into a framework of regional powers where the two principle powers, Armenia and Azerbaijan, will become more reliant on security partners Russia and Turkey," Broers said. "And I think a key implication of that is that they [Yerevan and Baku] will have less influence over the settlement process than they did before."
Chatham House's Broers said this week that Turkey's increased involvement "is challenging the status quo and the security balance that's existed and kind of held the peace -- however imperfectly -- over the last 15 years or so."
"It's a very difficult moment for multilateralism and for that deliberate democratic order on which the Minsk process was itself founded back in the 1990s," Broers said.
Dueling UN Statements
Aliyev reminded the world that "almost 20 percent of Azerbaijani territory remains under occupation of Armenia for almost 30 years" and renewed accusations against Armenia of "ethnic cleansing" in those occupied areas.
He called the Armenian presence "a major threat to regional peace and security" while accusing Yerevan of trying "to derail the [OSCE-led] peace process" in order "to maintain the current status quo of occupation and to annex the occupied territories."
Aliyev rejected the idea of "negotiations...for the sake of negotiations" and told the Minsk Group leaders that "statements are not enough. We need actions."
Pashinian, whose allied forces control Nagorno-Karabakh and surrounding Azerbaijani territory, pledged to the UN General Assembly that Yerevan would continue "its constructive engagement in the peaceful resolution of the conflict."
But he added that "the status and security of the Republic of Artsakh [Nagorno-Karabakh] is an absolute priority of the Republic of Armenia."
"Any attempt to resolve the conflict through military means represents a direct threat to regional security, democracy, and human rights," he said.
Trenches For Villagers Near The Line Of Contact
Azerbaijani authorities were overseeing months of trench-digging in many Azerbaijani-controlled villages this summer in the area of Agdam, which is bisected by the Line of Contact east of Nagorno-Karabakh.
Agdam has been a hot spot in this week's violence.
Some of the trenches were completed just two weeks or so before the latest fighting. An RFE/RL Azerbaijani Service correspondent saw newly installed surveillance cameras and military posts in some of the same communities during a visit on September 21.
"It was dug 15 days ago," a resident told RFE/RL. "They're going to cover the trench and make a shelter. If the war starts, we'll use it."
There were also Azerbaijani and Turkish flags decorating some of the roadsides in the area, seemingly reflecting Azerbaijani hopes placed in the potential support of Baku's strongest regional ally.
Aliyev Steps Up Threats
Days later, on September 25, Aliyev accused the Armenian side of "preparing for war." Speaking to the EU's special representative to the region, Toivo Klaar, he accused Yerevan of the "deliberate disruption" of the peace process, deployment of a cross-border effort to "sabotage the Line of Contact," and an "aggressive policy of Armenia against Azerbaijan."
Aliyev went on to accuse Armenian officials of "concentrating their forces not far from the Line of Contact," adding, "Of course we will defend ourselves."
Then came news on September 21 of the Azerbaijani authorities' call-up of reserve troops following a skirmish on the border with Armenia.
By September 27, each side was pointing the finger at the other as heavy casualties were reported in serious clashes that have now claimed dozens of lives.