U.S. Department of Defense

"In the exclusive economic zone of 11 miles from the border of Latvia, the National Armed Forces have identified a Russian "Kilo"-class submarine," the Latvian armed forces wrote on Twitter on Monday.

Latvia has repeatedly reported the Russian warships at the country's borders. On May 3, 2015, the Latvian armed forces spotted a squadron of Russian warships, including a submarine, within five miles of its territorial waters.