Some Israeli tanks moved inside Gaza, Palestinian residents said.
They said the tanks crossed about 200 meters into northern Gaza, in an area where they have operated frequently in the past. No clashes were reported.
The Israeli military had no immediate comment.
Israel has begun military operations against Gaza militants who have fired dozens of rockets at Israel in the past three days. Up to now the operations have been confined to airstrikes.
Turkey and Russia may conclude a deal on Crimea provided that Moscow recognises the Turkish Republic of Northern Cyprus (TRNC) as an independent state