A big treaty between the US and Russia is ending. This treaty is called New START. It helped control many nuclear weapons. The US and Russia worked together for years.
Russia said it will not follow the treaty rules. They also said the US did not agree to a plan. The plan was to make the treaty last longer. This news makes the world less safe.
The New START treaty started in 2011. It said each country could have 1,550 warheads. Countries could also check each other's weapons. This helped build trust.
Now, the treaty is ending. This is a problem. It means nuclear weapons are less controlled.
Russia stopped its part of the treaty before. Now they say countries are not following it. They say the US ignored their ideas.
This is a bad time for the treaty to end. There are many problems in the world. People worry about a new race for weapons. The United Nations is sad. They want Russia and the US to talk. The world is more unsure now.