"Naturally, this has caused a stir around the world and in the United States, as many understand the danger of this move, the risk of resuming the nuclear testing they've been conducting since the early 1990s. This could lead to a new escalation, a renewed arms race, and generally unpredictable consequences," Nebenzia said.
Moscow will continue to monitor the developments, the ambassador added.
"In response to our testing of new cruise missiles and nuclear-capable underwater weapons, President Trump stated that the United States is considering resuming nuclear testing. This is a serious statement. The consequences are still unknown," Nebenzia said.
The ambassador pointed out that Russian President Vladimir Putin had convened a meeting of the Russian Security Council, during which Putin emphasized that such statements must be taken "seriously."
Nebenzia added that "we must be prepared for such a development."