But because the United States is the biggest financial supporter of the United Nations and President Trump doesn't like the global organization, UN Secretary-General Antonio Guterres has to tread carefully.
When the Trump travel ban
hit, the UN leader did not criticize the border measure for several days. Guterres led the United Nations refugee agency for 10 years.
His spokesman in New York was cautious in comments to the press while Guterres was in Africa as massive demonstrations and most UN member governments condemned the ban on arrivals from seven countries plus a halt in refugees.
Guterres on Wednesday made it clear: He objects to the ban and does not believe it will stop terrorism.
In his first media appearance in New York since taking office, Guterres told reporters, "This is not the best way to best protect the US or any other country" against terrorism concerns.
Guterres, a former Portuguese Prime Minister, said, "I don't think this is the effective way to do so."
He added, "These measures should be removed sooner rather than later."
On the refugee ban, Guterres said, "When we adopt measures that have anxiety and anger, we help trigger ... recruitment mechanism" for terror groups around the world. In a written statement on Tuesday, Guterres said turning away people should not be based on discrimination linked to religion, ethnicity or nationality.
There have been reports the Trump administration will move to make severe cuts in US payments to the United Nations and its agencies. UN staffers have already been unnerved by what may be coming from Washington.
Guterres refused to add fuel to the fire, saying "the answer is to be firm in assessing our principles and open in engaging in constructive dialogue."
He said that's the combination he will use to be effective in dealing with the US administration or with any administration.
The UN leader met for the first time on Friday with the new US ambassador to the UN, Nikki Haley, who told reporters seconds after entering the building for the first time that "we will be taking names" of countries opposed to the United States.
Guterres said he had a "constructive discussion" with Haley, the former South Carolina governor.
He indicated he won't be making any comments on the US-UN relationship. "Sometimes we talk too much about the things that have not happened and when you talk too much about things that have not happened, you trigger the happening of those things," he said.
He vowed to show the value of the United Nations and conceded the organization does need reforms as the best way to get support from all member countries, including the United States and the new administration.
Guterres has had one phone call with President Trump so far but said he didn't know when or if a meeting will take place.
Until then, Guterres, whose diplomatic skills have been widely praised in previous international roles, will surely be tested.