Faced with a growing test of resolve for a new U.S. president who vowed while campaigning to get tough on North Korea, Donald Trump’s aides are pressing to complete a strategy review on how to counter Pyongyang’s missile and nuclear threats. Pyongyang’s latest missile launches and the assassination in Malaysia of North Korean leader Kim Jong Un’s estranged half-brother have added urgency, driving home the need for Washington to confront the security challenge.