Navy divers were searching for debris from the Chinese spy balloon that a U.S. fighter jet shot down off the coast of South Carolina, defense officials said on Sunday, as the fallout from the dramatic confrontation between the world’s two great powers showed no signs of easing. The recovery effort, which is expected to take days, began not long after debris from the balloon hit the water on Saturday, a defense official said. He added that a Navy ship had arrived on the scene, and that other Navy and Coast Guard ships, which had been put on alert, had also been dispatched.

The shooting down of the balloon, occurring at the end of a remarkable week of high-stakes international drama playing out in the open skies and behind closed doors, introduced a new phase in the increasingly tempestuous relationship between the United States and China, as each vies to be the pre-eminent world power across the economic, military and technological realms — with intelligence-gathering occupying a critical role in their competition. That a confrontation over a single surveillance balloon deemed harmless by the Pentagon could destabilize diplomacy between the two countries showed the difficulties of putting “guardrails on the relationship,” a goal stated in those terms by President Biden and his aides.

The Chinese government denounced the U.S. decision to down the balloon, calling it an “excessive reaction that seriously violates international convention.” The Foreign Ministry said China “retains the right to respond further,” and the National Defense Ministry said it would “use the necessary means to deal with similar circumstances.”