Updated

The U.S. and Israel are carrying out their largest joint military drill, simulating rocket attacks as real ones fired from Gaza are exploding in southern Israel.

President Barack Obama mentioned the joint drill in this week's presidential debate, calling it a testament to the strong military cooperation between the two countries.

About 3,500 Americans and 1,000 Israelis are participating in the exercise, called Austere Challenge 2012. The armies say they are practicing their ability to work together to thwart a variety of threats that face Israel.

Reporters were invited to view a training area near a Tel Aviv-area beach, where a Patriot air defense battery was deployed as part of Wednesday's exercise simulating incoming rockets.

Also this week, soldiers practiced a response to a chemical and biological attack.