The United States plans to send Ukraine a second and even larger batch of cluster munitions in the near future, reports The New York Times.

One official told the publication that the weapons played a key role in helping Ukraine “keep the momentum” that the UAF has recently built on the southern front.

The Ukrainian military also says that US cluster munitions have become a powerful addition to existing weapons and a necessary replacement for dwindling stocks of 155mm artillery shells.

“They are very efficient. When our guys see how we use them against the enemy, their spirits rise,” Ukrainian marine Serhiy said anonymously.

Other Ukrainian soldiers are more reserved and say that cluster munitions are ineffective against dug-in Russian positions, which are the main obstacle, but good against unprotected infantry.

The United States has hundreds of thousands of such munitions and they may become “one of the only available means of replenishing Ukraine’s stockpiles” against the backdrop of a shortage of other weapons. This worries human rights activists who are demanding their ban around the world.

Recently, Human Rights Watch published a report that almost all the victims of cluster munitions around the world last year were recorded in Ukraine: 890 people out of 987.