US Secretary of State Rex Tillerson is delivering a message of support to European allies in Brussels but their concerns about President Donald Trump's foreign policy have created a rift on a host of issues.
European allies are troubled by Trump's "America first" rhetoric, his decision not to certify Iran's compliance with a nuclear deal and his withdrawal from the Paris climate change accord.
Tillerson also sought to reassure US diplomats posted abroad that his ideas to revamp the country's foreign service were bearing fruit, saying he would reveal a modernisation plan for the US State Department soon.
Tillerson, the former chief executive of Exxon Mobil, said his visit showed "the strong commitment the US has to the European alliance, the important role that the European alliance plays in our shared security objectives".
Before a lunch with the European Union's foreign ministers, Tillerson stressed "shared values, shared objectives for security and prosperity on both sides of the Atlantic."
In his first substantive public comments since reports last week of a White House plan for CIA Director Mike Pompeo to replace him, Tillerson said despite "a little criticism", he was on top of his job.
"While we don't have any wins on the board yet, I can tell you we're in a much better position to advance America's interests around the world than we were 10 months ago," he told senior US diplomats and US embassy staff at the US mission to Belgium in Brussels.
Tillerson's trip will also take him to Vienna and Paris but it has been overshadowed by the reports that he could be fired.
Diplomats said EU government face a dilemma because Tillerson's views are more closely aligned with theirs but may not reflect those of Trump.
In a speech in Berlin before flying to Brussels, German Foreign Minister Sigmar Gabriel warned that the European Union could no longer rely on the United States as its closest ally.
