In a shift that could put Washington at odds with Tokyo, U.S. Secretary of State Rex Tillerson appeared to soften the United States' approach to the North Korean crisis on Tuesday, offering to begin talks without preconditions, including its long-standing demand that Pyongyang first give up its nuclear weapons.

"We're ready to talk anytime North Korea would like to talk, and we're ready to have the first meeting without preconditions," Tillerson said in a speech livestreamed from the Atlantic Council think tank in Washington. "Let's just meet. We can talk about the weather if you want. We can talk about whether it's going to be a square table or a roundtable if that's what you're excited about."

The top U.S. diplomat's comments struck a markedly different tone from past statements that have dismissed talks as unworkable unless the North first ditched its nuclear weapons. They also come just two weeks after Pyongyang, in what it characterized as a major "breakthrough," test-fired a long-range missile that experts said could strike most, if not all, of the continental United States.