Damage in Khan Yunis is outpacing other parts of Gaza for the first time, as Israel's offensive against Hamas pushes further south, according to university researchers' analysis of satellite data.

Twenty percent of structures in Khan Yunis have likely been damaged or destroyed by Dec. 11, according to data analyzed by researchers Corey Scher of CUNY Graduate Center in New York and Jamon Van Den Hoek of Oregon State University.

Israeli soldiers began fighting in the heart of Khan Yunis -- the second-largest city in Gaza -- in early December, according to the Israel Defense Forces.

"The entire leadership of the Hamas terrorist organization — both military and political — proliferated in the area of Khan Yunis," the IDF said.

The fighting in Khan Yunis marked a new phase of war and a change in tactics for the IDF and Hamas, according to Brian Carter, an analyst at the American Enterprise Institute's Critical Threats Project.

IDF operations in the south are happening faster and less methodically than they were in the north, Carter told ABC News. He said Hamas is "now mounting a deliberate defense" against the IDF, following the end of the temporary cease-fire.

Scher and Van Den Hoek used radar waves and satellite imagery from the European Space Agency's Copernicus Sentinel-1 to analyze and map damage in the Gaza Strip.

 

Data collected from Nov. 29 through Dec. 4 showed that likely damage was mostly concentrated in Gaza City and northern Gaza. However, the data also showed increasing damage in Khan Yunis, which continued to escalate over the following week.

Data from Dec. 4 through Dec. 11 revealed a significant cluster of likely damage in Khan Yunis as fighting between the IDF and Hamas intensified in the area.

Changes to the area are measured using a coherent change detection (CCD) approach, Scher and Van Den Hoek said. CCD uses an algorithm to create a new image based on combining two satellite images taken from the same location at different times.

In an update on Tuesday, the United Nations listed Khan Yunis as one of the main areas housing more than 1.1 million internally displaced people. The U.N. cautioned that exact figures were hard to ascertain because internally displaced people move around often.

Five U.N.-operated shelters in Khan Yunis were evacuated following a Dec. 6 warning from the IDF. On Dec.11 and 12, according to the U.N., the Nasser and Al Amal hospitals in the area were bombed multiple times.

At least 18,600 people have died and 50,000 people have been injured in the Gaza Strip since the start of the war, according to figures released by Gaza's Hamas-run Ministry of Health and the Hamas government media office. In Israel, at least 1,200 people have been killed and 6,900 others have been injured by Hamas and other Palestinian militants since Oct. 7, according to the IDF.