Iran live updates: Trump says US 'open' to Iran deal, tanker hit in Strait of Hormuz

Saudi Arabia's General Directorate of Civil Defense on Tuesday issued a rare public warning of a "potential danger" for the holy city of Mecca, as well as for the Jeddah and Taif regions.

The alerts instructed motorists to stay away from bridges, urged residents to avoid gatherings and to stay away from high-rise buildings.

The alerts lasted for around an hour, after which time the directorate said the danger to all three areas had passed. The warnings came amid intensified cross-border attacks between Saudi forces and the Iran-backed Houthi rebels in Yemen.

-ABC News' Lama Hasan and Joe Simonetti

The United Kingdom Maritime Trade Operations (UKMTO) Centre on Tuesday reported that a vessel was "struck by an unknown projectile" in the Strait of Hormuz.

The incident occurred on Monday evening, the UKMTO said in its alert. "There is no reported damage or environmental impact. Authorities are investigating," the message read.

Thirteen civilians were injured in Houthi strikes on Saudi Arabia on Monday, according to the spokesman for the Saudi Coalition Forces.

Civilian infrastructure in the cities of Khamis Mushait, Abha and Taif were struck by ballistic missiles and drones, with seven homes damaged, the spokesman said.

The Saudi military will "deal with these attacks responsibly and decisively," the spokesman said.

The Pentagon's Inspector General said in a report released Monday that the Pentagon acknowledged that the war in Iran has resulted in munitions shortfalls.

The "munitions expenditure in [Operation Epic Fury] has resulted in strategic inventory shortfalls and revealed industrial base bottlenecks for munitions resupply," including the building of solid rocket motors, explosives and propellants, the report stated.

The Defense Department is "working to streamline procurement processes and production lead times, and to stockpile critical materials, components, and selected munitions to respond rapidly to a contingency," the report stated.

The information was provided by the Defense Department in written responses sent to the Inspector General on Aug. 26, according to the report.

The Defense Department estimated the cost of the war to be $33.4 billion as of June 29, according to the report. The estimate included $7.4 billion of cumulative obligations, $22.3 billion for expended munitions and $3.7 billion in equipment losses, it said.

U.S. Central Command reported that Iranian strikes "damaged and destroyed hundreds of buildings and structures" at U.S. bases in the Middle East, according to the report.

U.S. diplomatic facilities in the region have also suffered $184 million in damage from Iranian strikes, the report said.

-ABC News' Luis Martinez