Armenian officials had already cut ties with Hungary, where Azerbaijani national and confessed killer Ramil Safarov had been serving a life sentence before his August 31 handover to authorities in Baku.
Yerevan also vowed to protest the presidential pardon in a letter to the states that co-chair the OSCE Minsk Group, which has been working for years to settle a frozen Azerbaijani-Armenian conflict.
Safarov had claimed in his defense that the victim, Armenian officer Gurgen Margarian, had urinated on an Azerbaijani flag and otherwise "insulted" that country.
With tempers still raging over the presidential pardon, Azerbaijani Defense Minister Safar Adiev on September 1 promoted Safarov from the military rank of lieutenant to major. The Defense Ministry also awarded Safarov over eight years in back pay in addition to giving him a free apartment.
Adiev went on to wish Safarov future success in his military career.
Armenian President Serzh Sarkisian had already expressed outrage and announced a suspension of all "diplomatic relations and all official contacts" with Budapest over Hungary's decision to return Safarov to Azerbaijan.
In a statement on September 2, Sarkisian also said his country is prepared to "fight and win" any war waged by Azerbaijan. He said Armenia does not want war but did not exclude that Baku would "impose" such a conflict.
Safarov's pardon, by Azerbaijani President Ilham Aliyev, also prompted questions by the United States.
Safarov was sentenced to life in prison in a 2006 trial for hacking the sleeping Armenian military officer to death at a NATO Partnership for Peace training mission in Hungary in 2004.
Aliyev offered no public explanation for the release, saying merely that Safarov was "released from serving his life sentence."
"I don't want to look back to that day," Safarov said in response to a question from RFE/RL's Azerbaijani Service after his return to Baku.
Minsk Group In The Middle
Azerbaijan and Armenia fought a bloody war in the 1990s over the ethnic Armenian territory of Nagorno-Karabakh, with a shaky cease-fire the only guarantee of peace since 1994.
The OSCE Minsk Group -- which is co-chaired by France, Russia, and the United States -- has mediated stubbornly unsuccessful peace talks ever since.
Azerbaijan's head of state quickly pardoned Safarov after the surprise handover by Hungary, which Budapest says was based on the European Convention on the Transfer of Sentenced Persons.
WATCH (in Azerbaijani): Ramil Safarov is greeted by family and well-wishers on his arrival in Baku after the Hungarian handover (Video by RFE/RL's Azerbaijani Service):
Hungarian authorities have said they were given assurances by Baku that Safarov would serve out his sentence in his homeland.
"This [did] not happen suddenly," Vilayet Guliyev, Azerbaijani ambassador to Hungary, told RFE/RL's Azerbaijani Service. "We had been working on this for many months. The extradition process from beginning to end was done by order of the Azerbaijani president and implemented by the embassy."
'Assurance' From Budapest
Hundreds of people protested outside the Hungarian consulate in Yerevan early on September 1, burning the Hungarian flag and throwing eggs, tomatoes, and coins.
Armenian President Sarkisian had said after an emergency meeting of his National Security Council on August 31 that Hungary made a "grave mistake." He said officials within Hungary's Foreign Ministry and parliament had offered assurances over a possible handover “during contacts in recent days.”
Sarkisian said that, instead, the release has sent a message of acceptance for "a murder committed on the basis of religious or ethnic hatred" that his country "cannot tolerate."
“The government of Hungary, at different levels, including the highest, has consistently and up until the last moment assured the government of Armenia that it will not take any steps whatsoever, which would result in the termination of serving justice by the perpetrator of a heinous murder and explicitly excluded any option for the execution of the transfer,” the Armenian Foreign Ministry said in a statement.
Armenia and Hungary, which is a member of the European Union and of NATO, do not have embassies in each other's capitals.
Hungary has nationalism issues of its own, with Viktor Orban's right-wing Fidesz government accused by political opponents recently of tolerating ethnically and nationalistically loaded remarks to avoid alienating the far right.
Washington Seeks Answers
U.S. President Barack Obama's administration has demanded an explanation from Hungary and expressed "deep concern" at the development, which it suggests could complicate efforts to maintain stability and security in the region.
“President [Barack] Obama is deeply concerned by today’s announcement that the President of Azerbaijan has pardoned Ramil Safarov following his return from Hungary,” Tommy Vietor, a spokesman for the U.S. National Security Council, said in a statement.
“We are communicating to Azerbaijani authorities our disappointment about the decision to pardon Safarov,” Vietor said. “This action is contrary to ongoing efforts to reduce regional tensions and promote reconciliation.”
“The United States is also requesting an explanation from Hungary regarding its decision to transfer Safarov to Azerbaijan,” he added.