No one expects the US to attack North Korea-- the scale of attack required would exhaust our military resources-- we fired 59 cruise missiles at an airbase in Syria and barely damaged it as it was back in use in a few days. We will need many, many times that destructive power, and more important, we need to find a way to target NK's fortified, hidden, and mobile weapons. We cannot avoid telegraphing our attack and we put our troops, aircraft, and carriers at risk. Neither China nor Russia would allow an attack by us on North Korea a country they both border-- they will arm North Korea with anti-aircraft and ant-imissile weapons like we provided to South Korea, and provide NK with support and weapons that can threaten our bases in Japan, and our carriers, keeping them far off shore and we will not attack with that kind of defensive threat from the Russians and Chinese. But Russia and Chinese also do not want a nuclear North Korea-- so they need to put economic screws to NK.