North Korea officially declared an end Friday to its diplomatic dalliance with the U.S. But experts say it’s been clear for some time that President Donald Trump’s bold but risky effort to sweet talk Kim Jong into relinquishing his nuclear weapons never really went anywhere. Two high-profile meetings with North Korea’s leader bought Trump a hiatus from bellicose rhetoric and nuclear tests, but Kim never stopped building nuclear warheads and the missiles to deliver them, U.S. intelligence officials and private analysts say. Now, on the second anniversary of that first Trump-Kim summit in Singapore, North Korea is renouncing the diplomacy while promising to expand its weapons program, even as experts say it is ever closer to perfecting a long-range missile capable of reaching and destroying an American city.