Iran’s top diplomat insisted on Sunday that there would be no military solution to the United States’ war against Iran, with talks on ending the conflict apparently at an impasse.

A campaign of heavy bombardment failed to bring a decisive close to the war launched by the US and Israel in late February, and Washington in recent weeks has dialed back military operations in favor of economic pressure.

The main point of contention remains Iran’s attempt to blockade the Strait of Hormuz where a UK maritime agency reported on Sunday another tanker struck by an unknown projectile.

“If our enemies again choose the path of military confrontation, our response will be stronger than before, and we will defend ourselves with even more force,” Iranian Foreign Minister Abbas Araghchi said at a gathering of foreign ambassadors.

“There is no military solution, nor any solution based on new sanctions,” he continued, adding “only negotiations based on justice and fairness” could end the conflict.

The two sides agreed a memorandum of understanding in June that spelled out a framework for a permanent resolution, but Iranian attacks on vessels in the Hormuz prompted a return to US military operations.

On Sunday, the British maritime security agency UKMTO said a tanker in the Hormuz “reported being struck by an unknown projectile, causing damage to the engine room”, though the crew were reported safe and no environmental impact was recorded.

The agency did not specify the date of the incident, the vessel’s origin or destination, or whether it was an oil tanker or LNG carrier.

Iranian and US officials last week held indirect talks on the sidelines of the UN General Assembly, with Tehran saying it presented seven conditions for reopening the strait.

Iran has demanded, among other things, a ceasefire across the Middle East, the unfreezing of its assets abroad, the lifting of sanctions on its oil sector and an end to the US naval blockade.

Trump, however, rejected the proposal, while leaving the door open both to further talks or renewed military operations.

Iranian foreign ministry spokesman Esmaeil Baqaei on Sunday characterized the latest US counterproposal as being “in line with their previous proposals concerning nuclear issues”.

“We have clearly indicated that we are focusing on the issue of the Strait of Hormuz,” he said, adding that reopening the waterway required “an end to the disruptions to Iranian commercial maritime traffic and the lifting of sanctions”.