Planned negotiations between the United States and Iran, which were scheduled to resume in Switzerland this weekend, have been canceled as military clashes between the two countries continue to escalate, according to sources familiar with the matter.

The Wall Street Journal reported that the latest round of talks was called off because of the ongoing hostilities, casting uncertainty over efforts to advance negotiations beyond the preliminary agreement reached earlier this month.

The development came as Iranian Foreign Minister Abbas Araghchi asserted that Iran holds exclusive authority over maritime traffic through the Strait of Hormuz under the preliminary agreement reached with President Donald Trump. He warned that attempts to bypass Iran’s authority could trigger additional confrontations similar to those seen in recent days.

Araghchi’s remarks directly contradict the U.S. position that the agreement does not grant Iran control over the vital international waterway and that commercial vessels should not require Iranian permission to transit the strait.

His comments followed several days of military exchanges between Iran and the United States. The latest fighting began after Iranian forces attacked a vessel attempting to pass through the Strait of Hormuz while navigating near the coast of Oman. Tehran, which has sought to redirect maritime traffic to a separate route closer to its own coastline, had warned ships against using the alternative shipping lane.

The renewed violence has unnerved shipping companies and raised fresh doubts about the reopening of one of the world’s most critical maritime chokepoints. The disruption threatens one of the principal achievements of President Trump’s preliminary agreement with Iran, which envisioned moving negotiations into a second phase focused on more contentious issues, including Tehran’s nuclear program.

The negotiations had been expected to resume in Switzerland later this week but have now been postponed indefinitely because of the fighting, according to sources cited by the Wall Street Journal.

“Managing and fully restoring maritime traffic in the Strait of Hormuz is Iran’s responsibility,” Araghchi said. “No other country or entity has responsibility or authority in this matter.”

U.S. Ambassador to the United Nations Mike Waltz warned that Washington would respond forcefully to any additional attacks on commercial shipping.

“If the Iranian regime thinks for a moment that President Trump will sit idly by, stand idly by, while Iran continues to attack international shipping without response or our bases without response, they are greatly mistaken,” Waltz said on Fox News. “And they have seen that loud and clear over the last several nights.”

In recent days, Iran attacked two commercial vessels—a container ship and an oil tanker transporting Qatari crude. The United States responded with strikes against Iranian communications facilities, drone sites, and missile positions along the Strait of Hormuz. Iran subsequently expanded the conflict by launching attacks against Kuwait and Bahrain.