Israeli troops killed four militants attempting to infiltrate from Lebanon, the army said Tuesday, as tensions run high along the border between the two countries.

The Israeli army denied it had been using the incendiary weapon white phosphorus in either Gaza or south Lebanon after Human Rights War accused it of doing so last week.

It did not immediately comment on Tuesday’s NNA report.

The international community fears the opening of a second front in the conflict, with Lebanon’s Iran-backed Hezbollah group joining Hamas in the fight against Israel.