A Russian-controlled corridor linking ethnic Armenians in Armenia with the breakaway Azerbaijani territory of Nagorno-Karabakh was temporarily closed early on November 13 after a violent incident at a checkpoint.
Baku says the closure came after an explosive device was thrown at one of its checkpoints along the corridor, injuring three Azerbaijani soldiers.
The Azerbaijani Prosecutor-General's Office and Defense Ministry blamed an Armenian national and "a group of criminals" for what it said was "a terrorist act" and they said an investigation was under way.
A video that appeared online after the border incident shows a man exiting a white car and throwing something toward an Azerbaijani checkpoint ahead of an explosion. Another video shows Russian peacekeepers detaining a man.
Early reports said the Stepanakert-Susa (Shushi in Armenian)-Berdzor road -- known as the Lachin corridor -- was closed to traffic in both directions. Later, ethnic Armenian authorities in Nagorno-Karabakh said the vital link had been reopened.
A peace deal has been mostly holding but interrupted by occasional instances of violence since 44 days of intense fighting between Armenia and Azerbaijan ended a year ago in major Azerbaijani gains on the ground in and around Nagorno-Karabakh and Russian troops keeping the Caucasus rivals apart.
The Russian soldiers have been deployed along the 25-kilometer-long and 5-kilometer-wide corridor for the past year.
On November 8, an Armenian civilian was reported killed and three more wounded, allegedly by Azerbaijani forces, while they were repairing water pipes outside the Azerbaijani-controlled city of Susa.
That is the same day that Armenians and Azerbaijanis commemorated the first anniversary of the end of their bloody six-week fighting in starkly different ways, highlighting the continued tensions over the breakaway region and surrounding districts.
The resulting peace deal was hailed as a triumph in Azerbaijan, but Armenian losses sparked months of massive protests in Yerevan to demand Prime Minister Nikol Pashinian's resignation.
Nagorno-Karabakh and seven nearby regions had been controlled by ethnic Armenians since a bitter war began as the Soviet Union crumbled in the late 1980s and then gave way to a three-decade "frozen conflict."