Russia delivered an ominous response Thursday after President Donald Trump unloaded a startling announcement that the United States would resume testing nuclear weapons, ending a more than three-decade hiatus.

"The United States has more Nuclear Weapons than any other country," Trump wrote late Wednesday. "This was accomplished, including a complete update and renovation of existing weapons, during my First Term in office. Because of the tremendous destructive power, I HATED to do it, but had no choice! Russia is second, and China is a distant third, but will be even within 5 years. Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis. That process will begin immediately. Thank you for your attention to this matter!"

Experts brutally fact-checked Trump's claims, with one expert asserting "nothing" Trump wrote was true. He also faced intense criticism from lawmakers in Congress.

Russia also responded to Trump's announcement with a grim warning if the U.S. broke the decades-long moratorium on testing.

A Kremlin spokesman told media outlets, "If someone departs from the moratorium, Russia will act accordingly."