TEL AVIV, Israel — Israeli forces are making their deepest incursion inside Lebanon since they withdrew from the country over a quarter-century ago, despite a nominal U.S.-brokered ceasefire and the first direct talks between the countries in decades.

The Israeli advance presents a challenge in the emerging deal to extend the Iran war ceasefire as Tehran wants any agreement to end fighting in Lebanon, too. Qatar called it a “dangerous escalation.” Germany’s foreign minister said it was cause for serious concern, according to German press agency dpa. There was no comment by the United States.