A small Israeli ground force entered the southern Gaza Strip at dawn today.
Residents said the Israeli force included tanks and other armoured vehicles. There were no immediate reports of injuries or damage.
An Israeli army spokesman confirmed military activity in the area against what he called "terror threats". Israeli forces often carry out operations in border areas.
Tensions between Israel and Hamas, which took over the Gaza Strip in June after routing Palestinian President Mahmoud Abbas's Fatah forces, have increased sharply in recent days.