U.S. Secretary of State Antony Blinken called on Azerbaijan's president to ramp up efforts in bilateral peace discussions with Armenia. He spoke by telephone with Azerbaijani President Ilham Aliyev "to urge an immediate reopening of the Lachin corridor to commercial traffic," said State Department spokesman Ned Price.

Azerbaijan's foreign minister had previously said that his country does not obstruct traffic in the Lachin corridor, and that vehicles are free to use the road. Azerbaijan has pointed to Armenia's illegal exploitation of its natural resources, which lasted for about 30 years of occupation and intensified in recent years.

"He underscored that the risk of a humanitarian crisis in the Lachin corridor undermined prospects for peace between Armenia and Azerbaijan," Price said in a statement.

Blinken last week also spoke to Armenian Prime Minister Nikol Pashinian and voiced "deep concern for the worsening humanitarian situation in Nagorno-Karabakh" due to the blockage of the corridor.

For more than one month, protesters, who claim to be environmental activists opposed to illegal mining, have occupied the Lachin corridor, a 32-kilometer (20-mile) mountain road linking Karabakh to Armenia.

Blinken has been active in mediating between the two former Soviet republics, increasing U.S. influence on an issue long dominated by Russia.

Armenia, with a large diaspora in the United States, enjoys support in Congress where a group of lawmakers last week urged Blinken to consider sanctions on Azerbaijanis responsible for the blockade.

Led by Representative Frank Pallone, a Democrat, the lawmakers warned in a letter of a "potential humanitarian catastrophe" without "immediate action" by the United States.

Officials in Yerevan have grown increasingly wary of Russia – formally an ally through a mutual self-defense treaty – for not doing more to end the blockade, especially since Russian peacekeepers are deployed in the corridor. Russia blamed Armenia for a breakdown in bilateral peace talks with Azerbaijan.

Azerbaijani President Aliyev said in October that clearing mines that have been planted by Armenia on occupied Azerbaijani territories will take nearly 30 years and cost $25 billion.

Baku also highlighted that Yerevan is not fulfilling its obligations under a statement signed after the Karabakh war in 2020, including the withdrawal of Armenian armed forces from Azerbaijani territory, adding that Armenia abuses the Lachin road for military provocations and obstructs the opening of all transport communications in the region.

Relations between the former Soviet republics of Armenia and Azerbaijan have been tense since 1991 when the Armenian military illegally occupied Karabakh, a territory internationally recognized as part of Azerbaijan, and seven adjacent regions. Clashes erupted on Sept. 27, 2020, with the Armenian Army attacking civilians and Azerbaijani forces, violating several humanitarian ceasefire agreements.

During the 44-day conflict, Azerbaijan liberated several cities and around 300 settlements and villages that had been occupied by Armenia for almost 30 years. The fighting ended with a Russian-brokered agreement on Nov. 10, 2020, which was seen as a victory for Azerbaijan and defeat for Armenia. However, the ceasefire has been violated several times since then.