The North has also put forward its own terms for talks, including the lifting of United Nations sanctions for North Korea’s recent nuclear and missile tests, a precondition the United States is unlikely to accept.

Still, the fact that North Korea has recently begun at least responding to American and South Korean overtures for dialogue represents a change.

“They are keeping the door open for possible negotiation,” said Cheong Seong-chang, an analyst at Sejong Institute, south of Seoul. He said the North might wait to accept the invitation until after the United States and South Korea ended their joint military exercises at the end of April.

Analysts have suggested the North could declare victory to its people once the exercises end, claiming its tough talk drove the Americans to halt what it characterizes as possible plans for invasion. Ending the exercises, and not repeating them, is one of the demands the North put forward on Thursday as a prerequisite for negotiations.

Jae H. Ku, director of the U.S.-Korea Institute at the Paul H. Nitze School of Advanced International Studies at Johns Hopkins University, said he believed China had played an important role in the toned-down North Korean language, in part by publicly criticizing American military operations in the region in a way that gave the North some face-saving cover for its anxiety over the joint exercises. At the same time, Mr. Ku said, he was sure that China, presumed to be the only country with real leverage with the North, had been privately pressuring the North Koreans to scale back their threats.

One of the first attempts to calm the confrontation came last Thursday when the government of President Park Geun-hye of South Korea ended weeks of tough talk with a vague offer of dialogue. The government also allowed a charity to ship tuberculosis medicines to North Korea, and authorized factory owners from the South to try to meet North Korean officials to discuss reopening a joint industrial park that Pyongyang temporarily closed last week. For now, the North has refused to meet the factory owners.

Then, last Friday, Secretary of State John Kerry, on a visit to the region focused on the North Korea crisis, said “our preference would be to get to talks” and supported the South’s efforts to reach out. The United States had earlier postponed a ballistic missile test.