The United States is facing a shortage of key missile stocks, including Tomahawk land-attack missiles and SM-3 interceptors, amid the ongoing US-Israeli offensive on Iran, CNN has reported.

Citing a senior US official, the report said on Monday that Washington anticipates a “major uptick” in attacks within the next 24 hours, while missile and interceptor reserves are depleting.

The official added that the initial round of strikes has reportedly succeeded in weakening Iranian defences. The upcoming phase is expected to focus on targeting Iran’s missile production facilities, unmanned aerial vehicles and naval capabilities.

The Pentagon is also facing a shortage of Patriot missiles, as Ukrainian air defences have used a significant portion of the stockpile over the past four years of war with Russia.

Read More: Trump warns of longer Iran war as Riyadh, Beirut hit

Since Saturday, the US-Israeli joint campaign has yielded significant claimed results, the US Central Command said, noting that all 11 Iranian vessels in the Gulf of Oman had been destroyed.

US President Donald Trump claimed that 49 Iranian leaders had been killed, including Supreme Leader Ali Khamenei. US B-2 stealth bombers also struck Iran’s hardened ballistic missile facilities overnight on Sunday.

Meanwhile, at least six US service members have been killed and 18 others seriously wounded since the operations began.

Iran has retaliated with drone and missile strikes targeting Gulf countries which are home to US military assets.