Israel and Hezbollah agreed to a‌ cease-fire Friday, a U.S. official told TIME, after a fresh exchange of strikes risked derailing Washington-Tehran talks for a permanent truce in the Iran war.

The halt in hostilities is understood to have come into effect at 4 p.m., local time.

There has yet to be an official confirmation of a cease-fire in Lebanon from either Israel or Hezbollah. TIME has reached out to the relevant parties for comment.

The U.S. and Iran peace talks, set to start anew in Switzerland Friday after the memorandum of understanding was signed earlier in the week, were abruptly postponed amid the flare-up of violence.

The White House on Thursday night said Vice President J.D. Vance would not be travelling to Europe to lead the U.S. delegation as “the plans for the upcoming technical talks have not been finalized.”

“The logistics of these negotiations have never been simple or predictable, we look forward to beginning technical talks as soon as possible,” a spokesperson said.

Lebanese broadcaster Al Mayadeen reported that Iran’s delegation postponed their travel to Switzerland due to the hostilities in Lebanon.

The latest exchange of strikes between Israeli forces and the Iran-backed Hezbollah militant group killed at least 18 people in Lebanon, according to the country’s Health Ministry.

Lebanese President Joseph Aoun condemned the intensified fighting as a “dangerous escalation.” 

Four Israeli soldiers were ​killed by Hezbollah ​militants. “Israel will not tolerate attacks on our soldiers or our territory, and it will exact a very heavy price from Hezbollah for these attacks,” said Israeli Prime Minister Benjamin Netanyahu, following the overnight exchange.

The Israel Defense Forces (IDF) said it had struck “80 command centers, terrorists, launch positions, and additional terrorist infrastructure” across southern Lebanon in response to what it described as “Hezbollah's repeated and blatant violations” of the initial cease-fire that came into place in April but has had little effect.

The violence was a significant test of the U.S.-Iran memorandum, as the first term states that upon signing, “the United States of America and the Islamic Republic of Iran and their allies in the current war” declared the “immediate and permanent termination of military operations on all fronts, including in Lebanon.”

But Israel was not a party to the negotiations, and Netanyahu earlier this week ruled out any immediate withdrawal of troops from Lebanon.

U.S. President Donald Trump and Vance have both aired their frustrations with Israel amid efforts from Washington and Tehran to finalize a permanent truce in the Iran war during their own extendable 60-day cease-fire.

Esmaeil Baghaei, Iran’s Foreign Ministry spokesperson, on Friday said the United States bears responsibility ​for the Israeli strikes in Lebanon, citing the first clause of the memorandum.

Tehran will “take all necessary measures to protect its interests, security, and rights and those of its allies,” he said.