BONN, Germany — When President Trump met with Prime Minister Benjamin Netanyahu of Israel at the White House on Wednesday, Secretary of State Rex W. Tillerson was conspicuously absent. He was on his first flight overseas as America’s top diplomat, pretty much alone.

Mr. Tillerson, who has no government experience, also missed two other important occasions in Washington this week: a lunch with Russia’s ambassador and Mr. Trump’s meetings with the prime minister of Canada. He has yet to hold a news conference.

Among the eight senior State Department staff members who accompanied Mr. Tillerson on Wednesday to Bonn, five are serving in temporary positions.

Mr. Tillerson was not expected to do much talking, at least publicly, at a Group of 20 foreign ministers’ meeting here on Thursday, which will lay the groundwork for the Group of 20 meeting in July.