Query: When did Turkey close off its border with Armenia?
Context: Despite this, for most of the 20th century and early 21st century, relations remain tense and there are no formal diplomatic relations between the two countries due to Turkey's refusal to establish them for numerous reasons. During the Nagorno-Karabakh War and citing it as the reason, Turkey illegally closed its land border with Armenia in 1993. It has not lifted its blockade despite pressure from the powerful Turkish business lobby interested in Armenian markets.