image copyrightReutersimage captionSmoke and flames are seen after an Israeli air strike in the northern Gaza Strip
Israel's military carried out air strikes on the Gaza Strip overnight on Thursday after Palestinian militants there sent more incendiary balloons into southern Israel.
It is the second round of strikes in three nights after multiple attacks with balloon-borne devices.
The violence will further strain a fragile ceasefire in place since 21 May.
The truce followed 11 days of fighting between Israel and militants in Gaza.
This week's air strikes are the first under Israel's new Prime Minister Naftali Bennett, whose coalition replaced long-standing leader Benjamin Netanyahu on Sunday.
There were no immediate reports of casualties.
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The Israeli Defense Forces (IDF) said the strikes hit military compounds and a rocket launch site belonging to Hamas, the militant group which runs Gaza. It said the targets were in Gaza City and Khan Younis, in southern Gaza.
The IDF called it retaliation for the launching of "arson balloons" towards Israeli towns.
In recent years, militants have frequently sent helium balloons and kites carrying containers of burning fuel and explosive devices over the Gaza border.
The devices have caused hundreds of fires in Israel, burning thousands of hectares of forest and farmland.
image copyrightGetty Imagesimage captionPalestinians release balloons with incendiary devices attached into Israel (file picture)
Hamas militants responded to the jet strikes by firing heavy machine guns, AFP news agency said.
Rocket-warning sirens rang out in Israeli border communities – but security sources told the BBC no rockets were fired from Gaza, and the trigger was gunfire towards a military drone.
media captionTwo children from Gaza City and Israel describe their experience of the Israel-Gaza conflict