The United States and Iran have exchanged fire in the Strait of Hormuz, prompting fears that the already fragile ceasefire between the warring nations could collapse. The flare-up in fighting on Thursday came as Washington awaits a response from Tehran to its latest proposals for an agreement to end the war, which began with joint US-Israeli air strikes on Iran on February 28. Recommended Stories list of 3 items list 1 of 3 Iran says it attacked US Navy ships after they targeted Iranian tanker list 2 of 3 Seafarers trapped in limbo as US and Iran clash in Strait of Hormuz list 3 of 3 Oil prices jump as US, Iran trade fire in Strait of Hormuz end of list Here’s what we know about how significant the latest clashes are and what each side is trying to achieve. What happened in the Gulf on Thursday?…