A US warship that intercepted drones and missiles near the coast of Yemen on Thursday encountered a larger and more sustained barrage than was previously known, shooting down 4 cruise missiles and 15 drones over a period of 9 hours, according to a US official familiar with the situation.

The USS Carney, an Arleigh-Burke class destroyer that traversed the Suez Canal heading south on Wednesday, intercepted the missiles and drones as they were heading north along the Red Sea. Their trajectory left little doubt that the projectiles were headed for Israel, the official said, a clearer assessment than the Pentagon's initial take.

A sustained barrage of drones and missiles targeting Israel from far outside the Gaza conflict is one of a series of worrying signs that the war risks escalating beyond the borders of the coastal enclave.

In addition to protests at US embassies across the Middle East, US and coalition forces in Syria and Iraq have come under repeated attack over the past several days.

On Thursday, Pentagon press secretary Brig. Gen. Pat Ryder said the missiles were fired by Iranian-backed Houthi forces in Yemen and were launched "potentially towards targets in Israel." At the briefing, Ryder said three land-attack cruise missiles and "several" drones.

Some of the projectiles were traveling at altitudes that made them a potential risk to commercial aviation when they were intercepted, the US official said. The drones and missiles were intercepted with SM-2 surface-to-air missiles launched from the USS Carney.

US interceptions of Houthi launches are exceedingly rare, making the timing of this incident, as tensions rise in Israel, more significant. In October 2016, the USS Mason deployed countermeasures to stop an attempted attack in the Red Sea targeting the Navy destroyer and other ships nearby. In response, the US fired sea-launched cruise missiles at Houthi radar facilities in Yemen.

On Wednesday, one-way attack drones targeted two different US positions in Iraq, according to US Central Command. One of the attacks resulted in minor injuries. One day later, the At-Tanf garrison in Syria, which houses US and coalition forces, was targeted by two drones, which also caused minor injuries.

Early Friday morning in Iraq, two rockets targeted the Baghdad Diplomatic Support Center near the airport, which houses US military, diplomatic and civilian personnel, according to another US defense official. One rocket was intercepted by a counter-rocket system, while the second hit an empty storage facility, the official said. No one was injured as a result of the rocket attack.

The US has not assigned attribution for any of the recent attacks in Iraq and Syria, though Iranian proxies have carried out similar drone and rocket attacks against US forces in both countries in the past.

The US military has carried out strikes on Iranian-backed militias as a response to previous such attacks against US forces, but the Pentagon would not say anything yet about its intentions.

"While I'm not going to forecast any potential response to these attacks, I will say that we will take all necessary actions to defend US and coalition forces against any threat," said Ryder. "Any response, should one occur, will come at a time and a manner of our choosing."