Trump declined to comment on who is ultimately responsible for what happened. However, Secretary of State Mike Pompeo said that Washington identified some security officials and the Saudi government who believe they were involved in the death of the journalist and would take appropriate measures, including the revocation of visas to enter the country.
In case the US identifies the person responsible for the act they would have to judge it or revoke the visa so that it does not enter the country. But regarding Saudi Arabia, at first you would not have to take any action, since it is a partner country in the Middle East region, and that decision could be negative for the country.