Washington and Tehran have been at war since February 28, when the US and Israel launched surprise strikes against Iran, though months of on-off diplomacy have led to periods of relative calm.In what has become a familiar pattern, Trump last week had threatened to hit Iran "very hard" -- potentially with renewed attacks against energy infrastructure -- only to pull back on Saturday, saying the "perimeters" of a deal were there.Iran's foreign ministry, however, denied there were negotiations taking place."We are not currently negotiating with the United States. Our negotiations are with Oman to secure passage through the Strait of Hormuz," said foreign ministry spokesman Esmaeil Baqaei during a weekly press briefing.The Hormuz strait is a major sticking point in efforts to end the war. Since a ceasefire broke down, Iran has reprised a blockade of the critical trade corridor it first imposed early in the war, obstructing vessels attempting to pass and firing on commercial ships.Calling Tehran "duplicitous" for "openly and proudly" saying it was not negotiating, Trump wrote on social media: "Whether Iran wants to admit it or not, we are, in fact, talking of a solution to a problem that they have caused, for decades."He pointed to the United States' counter-blockade of Iranian ports, adding: "Nothing gets through to Iran, unless we want it to, and nothing will get through, unless a Deal, or Total Surrender, is accomplished."HormuzBefore the war, there was free passage through Hormuz, but Iran now insists on retaining control and charging fees, something the US rejects.Tehran has refused to let ships travel any route other than one that hugs the Iranian coast.On Sunday, Baqaei told state television that a deal was close on managing Hormuz together with Oman, which sits on the other side of the narrow waterway."We are now going to reach an understanding on a route acceptable to both sides -- neither the northern route nor the southern route -- but one that respects the sovereign rights of both sides and safeguards our national interests and security," he said.But he insisted that such an agreement did not mean the reopening of the strait.On Sunday, a tanker off the coast of Oman reported hearing an explosion nearby, the United Kingdom Maritime Trade Operations (UKMTO) Centre reported, but the ship and crew were all reported safe.'It begins tomorrow'