President Trump will host members of the United Nations Security Council at the White House Monday, a highly unusual meeting made even more startling because of his harsh criticism of the international institution during the campaign and since taking office.

U.S. Ambassador to the UN Nikki Haley is serving this month as the President of the Security Council, a role that rotates each month among the five permanent members: the U.S., Great Britain, France, China and Russia. There are 15 members of the group — but the others, right now including Egypt, Japan, Senegal, Bolivia, Ethiopia, Italy, Kazakhstan, Sweden, Ukraine and Uruguay are non-voting members.

Haley will be attending before the group returns to New York for scheduled Security Council meetings on Tuesday.

More from NBC News:

White House optimism on shutdown complicated by Trump demands

Here's the full list of Donald Trump's executive orders

Analysis: Trump's nowhere on half his presidential pledges

The president's budget outline proposed deep cuts in the U.S. contribution to the UN, which could dramatically impair its peacekeeping functions around the world.

Other high profile UN functions include refugee relief and vetting of refugee visa applicants to the U.S, the World Health Organization, UNICEF and the International Atomic Energy Agency in Vienna — the weapons inspectors who monitor Iran's compliance with the nuclear deal.