The United States is condemning the latest violence to hit South Sudan, which the U.S. says is the fault of rebel fighters who launched attacks in and around an oil town.

South Sudan has suffered massive violence since last December, causing more than 1.7 million people to flee their homes.

The U.S. said Thursday the latest attacks were carried out by rebels around Bentiu.

The U.S. said that the country's humanitarian crisis continues to reach "even more appalling levels" as fighting continues.

The International Crisis group said in a report Thursday that the warring sides are preparing for major offensives when the rainy season ends in the coming weeks.

The group said that renewed conflict is likely to be accompanied by widespread displacement, atrocity crimes and famine.