The United States provided Ukraine with cluster munitions. What is their effectiveness and danger?

In a controversial move, the US has agreed to supply Ukraine with cluster bombs for its counteroffensive against occupying Russian forces. President Vladimir Putin said Russia had a "sufficient stockpile" of cluster bombs and reserves the right to use them if they were deployed against Russians.

Cluster bombs are controversial and widely banned. Why is the US sending them to Ukraine? Source: AP / Mohammad Zaatari