As Biden and Xi gear up for a high-stakes meeting, experts have low expectations

WASHINGTON — U.S.-China relations, marred in the past year by a series of inflection points, have reached one of the most tense periods perhaps since 1972, when the two nations established diplomatic ties. A Chinese spy balloon. Close encounters in both the air and the Taiwan Strait. Diplomatic spats over the theft of technology, hacking and trade. A drought of military-to-military talks. Even the lapse of a panda agreement. All point to worsening relations that will hang over next week's meeting between President Joe Biden and China's President Xi Jinping, their first in-person meeting in about a year, and the…