The Israel Defence Forces (IDF) says two mortars launched from Lebanon landed in open territory in northern Israel Monday.
The IDF said it was striking back at the source of the launches.
A CNN team in southern Lebanon has heard frequent detonations in the border area Monday.
The IDF also reported the launch of an anti-tank missile from Lebanon toward the area of Netu'a in northern Israel.
“In response, IDF artillery is striking the sources of the fire,” the IDF said.
The IDF also said that overnight an “armed terrorist cell” was hit in southern Lebanon, just over the border from the Israeli area of Biranit.
The Lebanese militia Hezbollah says it attacked Israeli infantry close to the border "and achieved direct hits" on Monday morning.
Lebanon’s National News Agency reported six separate incidents of incoming fire Monday, five in the western sector and one in the east around Mhaibib where it says that "phosphorous" was used.
CNN is unable to confirm the use of phosphorous munitions Monday.
Remember: White Phosphorus is an incendiary weapon used to set fire to military targets. Its use is restricted under international humanitarian law - it can't be fired at or near civilian areas or civilian infrastructure.
Last week, the IDF responded to accusations about the use of white phosphorus in Lebanon, dismissing reports that the substance had been used for setting fires, but acknowledging that it does use it in some circumstances.
Some context: On the face of it, the crossfire on Lebanon’s border with Israel appears marginal, dwarfed by the scale and intensity of the Hamas-Israel war further south.
Yet this barely populated swathe of mountainous terrain could be the launching pad of a regional war, drawing in a myriad of actors, including Iran and the United States.
Hezbollah – an Iran-backed armed group that is also a regional force in its own right – dominates south Lebanon. It also operates alongside Iran’s elite Revolutionary Guard Corps in Syria, where the Israeli-occupied Golan Heights separates Israel from Tehran-aligned fighters.
Meanwhile, the US has deployed two of its largest aircraft carriers — including the nuclear-powered USS Gerald Ford — to the eastern Mediterranean. It is an ominous sign of what may come if the situation on the Lebanon-Israel border combusts into a full-scale war.