Were it not for the coronavirus pandemic, a top issue on Turkey’s agenda in April would have been the planned activation of the S-400 air defense systems that NATO member Turkey purchased from Russia.

Soon after delivery of the systems began in July 2019, President Recep Tayyip Erdogan set April 2020 as the time that the S-400s would become operational. He confirmed that timetable as recently as March 5 after talks with Russian President Vladimir Putin in Moscow in which the two leaders sealed a cease-fire deal in Idlib. “The S-400s are now our property. All parts have arrived, and [the systems] will become operational in April,” he told journalists accompanying him on the flight back home.

Despite such declarations of resolve at the highest level, the issue of the S-400 activation appeared completely off the agenda of the Erdogan government and its media as of April 14. Neither Erdogan nor other government officials have uttered a word on the matter since the beginning of the month. The pro-government media has neither reported nor asked questions about the activation plan, and none of its columnists has pondered the reasons for the silence. It looks as if the S-400s, which reportedly cost Turkey more than $2 billion, have been condemned to oblivion.

What could be behind this abrupt silence and inaction on a strategically significant issue that bears closely on Turkey’s place in the world and regional geopolitics?