Israel’s military and Iran-backed Hezbollah militants reportedly clashed in southern Lebanon on Tuesday, days before the U.S. is due to host delegations from Israel and Lebanon for talks.

According to the Associated Press, a ceasefire between Israel and Hezbollah, which was brokered by Washington, appeared to be nominal, potentially imperiling separate peace negotiations between the U.S. and Iran. Tehran has demanded that any agreement also includes an end to fighting in Lebanon.

Israeli Prime Minister Benjamin Netanyahu has said that Israel will expand its operations in Lebanon, adding that its forces are “seizing strategic areas” and aiming to fortify an area of southern Lebanon now under its control, the AP reported.

Hezbollah said it had launched rocket, artillery and exploding drone attacks on Israeli troops and vehicles, the AP said.

The reports come as talks between the U.S. and Iran to conclude their nearly three-month war face an uncertain trajectory. News outlet Al Jazeera has reported that indirect negotiations between Washington and Tehran have continued, despite an exchange of fire earlier this week. The U.S. stressed that a shaky ceasefire remained in place, although Iran has warned of retaliation should the truce be violated.

U.S. Secretary of State Marco Rubio said this week that it will take a “few days” for Washington and Tehran to reach a deal.

Media reports this week have suggested that the U.S. and Iran were close to a framework accord. The terms of the agreement included an extension to the ceasefire and a reopening of the Strait of Hormuz, a vital waterway off Iran’s southern coast through which a fifth of the world’s oil flows. The strait has been largely shuttered since the start of the war in late February, crimping oil supplies and driving crude prices higher.

Brent crude futures, the global oil benchmark, were last down by 3.2% at $96.44 a barrel. The contract is below recent peaks that topped $100 a barrel, but still far above pre-war levels, keeping concerns over an energy-induced inflation surge in place