National Security Adviser John Bolton listens as President Donald Trump holds a Cabinet meeting at the White House, April 9, 2018. Kevin Lamarque | Reuters

U.S. National Security Advisor John Bolton on Tuesday suggested that an audio tape of Jamal Khashoggi's murder may not implicate Saudi Arabia's Crown Prince Mohammed bin Salman. "In the assessment of those who have listened to it," the recording does not directly implicate bin Salman, Bolton said, adding that he had not listened to the tape himself. The former U.S Ambassador to the United Nations spoke to reporters in Singapore, where he and Vice President Mike Pence are attending the ASEAN-U.S. Summit and the East Asia Summit. The United States is not the only country holding a copy of the tape, and other nations' intelligence services are scrutinizing the recording on their own. Turkish President Recep Tayyip Erdogan said his country sent audio that allegedly captures the killing of the Washington Post journalist Khashoggi to Canada, Great Britain, France, Germany and Saudi Arabia.

Thoughts on North Korea and South China Sea

On North Korea, Bolton said President Trump was prepared to have a second summit with Kim Jong Un but didn't provide any details on timing or location. Pyongyang in June said it agreed to a vague deal to work toward the denuclearization of the Korean Peninsula, and the Trump administration has made much of its supposed success in making that agreement. But North Korea hasn't stopped working on its ballistic missile program, NBC News, citing U.S. officials, reported on Tuesday.