White House national security adviser Jake Sullivan, in separate calls on Monday with the leaders of Armenia and Azerbaijan, expressed concern over recent tensions between the two countries, the White House said in a statement.
Armenia accused Azerbaijan last week of sending troops across the border. Azerbaijan has denied this and said its forces only defended their side of the frontier.
Sullivan, who spoke with Armenian Prime Minister Nikol Pashinyan and Azerbaijan President Ilham Aliyev, "emphasized that military movements near un-demarcated borders are irresponsible and provocative," the statement said.
Sullivan also "underscored the need for the two countries to conduct formal discussions to demarcate their international border," it said.
(Reporting by Eric Beech; Editing by Mohammad Zargham and Rosalba O'Brien)
