WASHINGTON (Reuters) - Rex Tillerson arrived in Bonn on Wednesday on his maiden foreign trip as U.S. secretary of state to attend a summit of G20 top economies at a time when many are wondering how far President Donald Trump’s “America First” message will reshape U.S. foreign policy. From North Korean provocations and reports Russia has deployed a new cruise missile, to concerns about China’s actions in the South China Sea and conflicts in Yemen, Syria and Ukraine, there is no shortage of global challenges. Tillerson did not make any remarks on his arrival in Bonn. Senior U.S. officials said Tillerson’s two-day trip was mostly to listen to what G20 counterparts had to say, conceding that this might frustrate some.  Tillerson will also participate in a series of sessions on a shifting global order, cooperation with Africa and conflict prevention. It will be a prelude to the G20 leaders summit in Hamburg, Germany in July, which Trump is due to attend. “I think he is mostly going on a listening tour,” said a U.S. official who spoke on condition of anonymity, saying that may disappoint U.S. allies. “If our (guy) says, ‘well, I am just here to listen,’ that’s going to be dispiriting.” U.S. allies worry about Trump’s unpredictability. They wonder how far he will go in warning China and Iran about their behavior, whether he will back out of long-standing treaties and trade deals, tear up the nuclear agreement with Iran, build a border wall with Mexico, or cozy up to Moscow. Tillerson, the former Exxon Mobil CEO, has international business experience but none in government. State Department officials said he would meet with counterparts from Britain, Saudi Arabia, Turkey, Italy and Oman while in Bonn, and participate in larger meetings on Yemen and Syria. He also will hold his first meeting as secretary of state with Russian Foreign Minister Sergei Lavrov at a time when Trump administration contacts with Moscow are under the spotlight with the resignation of national security adviser Michael Flynn. Flynn had been the new administration’s main contact for many foreign ambassadors to the United States.  “The conversation with Mr. Lavrov will be a very important one,” a senior State Department official said, speaking to reporters ahead of Tillerson’s departure. During his meeting with Lavrov on Thursday, Tillerson will seek “pragmatic and constructive cooperation in areas where our interests overlap,” the official said. “The obvious ones which have been discussed many times are counter-ISIS and counterterrorism would be areas that the Secretary would hope to develop some possible avenues for cooperation,” the official said. He will also press Russia to fully implement the Minsk peace accords to end violence in eastern Ukraine. The G20 is made up of developed economies and emerging nations such as China, India, Indonesia, Mexico, South Africa and Brazil. Jim Wilkinson, a senior adviser to former Secretary of State Condoleezza Rice, said it was vital for Tillerson to establish a relationship with fellow ministers during his first trip. “That chemistry with counterparts begins on the first trip,” he said. “Secretary Tillerson and his counterparts will be working on some of the toughest issues around the world and that’s going to require trust.”  While Tillerson has been on the job for just two weeks and may not be immersed in all subjects yet, Wilkinson said: “Foreign ministers will be understanding that in the early days he may not have all the answers, but they will want to know they have a conduit to someone who can speak for the U.S.” 