WASHINGTON (Reuters) - A meeting of NATO foreign ministers in Washington this week will discuss all elements of the threat posed by Russia and seek to agree on a package of measures to bolster the military alliance's presence in the Black Sea, a senior U.S. official said on Tuesday.
"The focus is on the defence and deterrence posture of the alliance in the Black Sea region," said the official, speaking to reporters on condition of anonymity to preview the NATO meeting.
The official said NATO ally Turkey remained an important partner to the United States, but emphasized that its planned purchases of S-400 missile systems from Russia was a concern.
"Our relationship is not being defined by the single issue of the S-400 but the S-400 is a deeply problematic issue for the United States," the official added.
(Reporting by Lesley Wroughton; Editing by Chizu Nomiyama)