The United Nations (UN) General Assembly opens today. It occurs just as the world body marks its 80th birthday. It's also a tense time for the global organization. Wars drag on in the Gaza Strip, Sudan, and Ukraine. With each one, the UN hasn't been able to resolve it. Besides these and other world crises, the UN is facing funding cutbacks too. They're mostly from the US. Under Trump, the US has rejected the UN’s many global missions. The US has also attacked the UN politically. Trump is leading under his America First agenda. And he has pulled the US from the UN’s World Health Organization. Trump has pulled the US from UNESCO too. It's the UN's educational body. Trump also has assailed the UN’s Sustainable Development Goals. These seek to end such ills as poverty and hunger. The US has voted against any mission that mentions them. The US is acting in a very "petty way,” Richard Gowan told NPR. Gowan is the UN’s director for the International Crisis Group. It's a think tank. Some UN officials said the US pullback has weakened the world body at a hectic time when its leadership is most needed. Anjali Dayal is a UN expert. Dayal works at Fordham University. Dayal told NPR that "the US is actively working to disrupt (the UN's missions)." Dayal said the US is hindering the UN's work in public health, gender equality, and poverty reduction. In its opening week, the General Assembly will take on a number of hard issues. They include perhaps recognizing statehood for Palestinians, Israel’s war on Hamas in Gaza, a climate summit, and the impacts of AI. António Guterres is the UN’s secretary general. He'll meet with a number of world leaders. But it’s unknown if Trump will be among them. Reflect: How do you think countries should work together when they don’t always agree? Photo of a high-level meeting to commemorate the 80th anniversary of the United Nations in New York City from Reuters.