Israel has launched airstrikes in the Gaza Strip targeting Hamas interests following a rocket attack.
This is the first time Israeli jets have bombed Hamas installations since the rivals agreed on a truce in August.
There were no immediate reports of damage or injuries in the aerial attack.
Unconfirmed local reports suggest Israeli warships were also part of the operation. The Palestinian news agency Ma'an said a Hamas military installation in northwest of Khan Yunis was targeted.
Israel Defence Forces (IDF) spokesperson Lieutenant Colonel Peter Lerner said: "The IDF will not permit any attempt to undermine the security and jeopardise the well-being of the civilians of Israel. The Hamas terrorist organisation is responsible and accountable for today's attack against Israel."
The overnight bombardment on Friday, 19 December, was carried out following a rocket attack in southern Israel in Eshkol region just near the Gaza Strip. The rocket fire did not cause any damage.
Him Yelim, the chief of Ezhkol Regional Council, was quoted as saying: "Whoever thinks that military deterrence is the route to peace and quiet for the Gaza bordering regions doesn't understand that wars are won by diplomats. After Protective Edge, the state had a unique opportunity to bring about a long-term settlement. But instead we find ourselves with a ticking clock until the next round of escalation, and the next war."
In August, fighting between Israeli forces and Hamas fighters claimed more than 2,200 lives, most of them Palestinians. The seven-week violence ended following a truce agreement.