WASHINGTON - The leaders of Armenia and Azerbaijan signed a peace agreement at the White House on Friday, ending a decades-long border conflict.

Armenian Prime Minister Nikol Pashinyan and Azerbaijani President Ilham Aliyev witnessed the initialing of the agreement by their foreign ministers. The two countries will take further steps to eventually sign and ratify the agreement, the declaration said.

"The conditions have been created for our nations to finally embark on building good neighborly relations on the basis of the inviolability of international borders and the inadmissibility of the use of force for the acquisition of territory after the conflict that brought immense human suffering," it said.

Aliyev told reporters the same day that the formal signing of the agreement should not take very long.

Armenia and Azerbaijan have been at loggerheads over the mountainous Nagorno-Karabakh region since 1988. Peace talks have been going on since 1994 when a ceasefire was agreed on, despite sporadic clashes since then.