Tensions have flared anew Azerbaijan installed a road checkpoint at the start of the Lachin Corridor, the only route linking Armenia to the disputed Nagorno-Karabakh territory.
Karabakh is internationally recognised as part of Azerbaijan, but home to mostly ethnic Armenians. Azerbaijan committed to keeping the route open as part of a Russian-brokered ceasefire in 2020 that ended a six-week war between the two countries.
The stand-off is seen as a test of Russia's resolve to mediate disputes in the region. Armenia - formally an ally of Russia through a mutual self-defence pact - has repeatedly called on Moscow to use its peacekeeping force to stop what it calls Azerbaijan's "gross violation" of the peace deal.
Azerbaijan said it had established the checkpoint in response to what it said were Armenian weapon supplies to Nagorno-Karabakh. Yerevan denies that charge.
The talks in Washington were not expected to yield a breakthrough. Blinken was initially meeting delegations from both countries separately before a three-way meeting was due to start later on Monday.
After its meeting with the United States' top diplomat, Armenia's foreign ministry said relations between Azerbaijan and Armenia had been "discussed" and they had "touched upon the humanitarian situation as a result of Azerbaijan's illegal blockade of the Lachin Corridor".
Negotiations over a longer-term peace deal between the two sides after another military flare-up last year quickly stalled as Armenia pushed for the European Union and France to have a bigger mediating role, but Azerbaijan rejected.
French Foreign Minister Catherine Colonna visited Baku and Yerevan last week, where she clashed with her Azerbaijani counterpart Jeyhun Bayramov after calling on Azerbaijan to free up the road to the disputed region.
Washington has previously said it was "deeply concerned" by Azerbaijan establishing the checkpoint.
(Reporting by Jake Cordell in Tbilisi; Editing by Nick Macfie)
