(Bloomberg) -- Azerbaijan pulled out of planned peace talks with Armenia in Washington after it accused a senior US official of making “unacceptable” criticism of Baku’s military takeover of the Nagorno-Karabakh region.

Azerbaijani Foreign Minister Jeyhun Bayramov won’t attend US-mediated negotiations with his Armenian counterpart, Ararat Mirzoyan, on Nov. 20 because of Assistant Secretary of State James O’Brien’s “one-sided” comments, the Foreign Ministry in Baku said Thursday. Azerbaijan will refuse visits by senior American officials and the US risks losing its role as a mediator, according to the ministry’s statement.

“There’s no chance of business as usual” with the government in Baku until a peace agreement is reached with Armenia, O’Brien told a House Foreign Affairs Committee hearing on Wednesday. The US canceled a “number of senior-level engagements” with Azerbaijan after the Sept. 19-20 lightning attack that prompted an exodus of 100,000 Armenians from Nagorno-Karabakh, he said. 

Washington is “very closely” monitoring troop movements for any sign Azerbaijan intends to invade Armenia itself to create a transit corridor to its exclave of Naxcivan, O’Brien said, even as Baku has declared it has no such intention. The Biden administration also has no plans to renew an annual waiver to legislation from 1992 that bans direct US assistance to Azerbaijan, he said.

Azerbaijan’s attack effectively ended a 35-year conflict with Armenia over Nagorno-Karabakh after the territory’s local Armenian population declared independence amid the collapse of the Soviet Union. It gained control of some of the region, which is internationally recognized as part of Azerbaijan, as well as seven surrounding districts occupied by Armenia for decades in a 2020 war that killed thousands before Russia brokered a truce deal.

While Azerbaijani President Ilham Aliyev urged Armenians to remain in Nagorno-Karabakh, practically the entire population fled to Armenia, fearing for their security despite his pledge to uphold their rights.

The next few weeks will be “critical” in reaching a peace deal between the two sides, O’Brien told the congressional hearing. While Armenian Prime Minister Nikol Pashinyan “seems willing to take chances for peace, the question really is whether President Aliyev is willing to do that.”

The State Department is working to produce a “comprehensive” record of events that led to the Azerbaijani attack in Nagorno-Karabakh and the departure of its Armenian population, O’Brien said.

The US is insisting on “the protection of the culture” and that the people who left “receive adequate information so that they can make a real choice about their future and know that they have the viable opportunity to return,” he said.

©2023 Bloomberg L.P.