Washington: Less than two weeks into the US war on Iran, the US has used 'years' worth of key munitions, raising concerns about the cost of the conflict and the strain on American weapons stockpiles, according to media reports.

According to Anadolu Agency, citing three people familiar with the matter, a report by The Financial Times said the rapid expenditure includes large numbers of Tomahawk cruise missiles. One source described it as a 'massive expenditure of Tomahawks,' adding that 'the navy will be feeling this expenditure for several years.'

The conflict, which began on Feb. 28, has already cost more than $11 billion in its first six days, according to Pentagon officials briefing lawmakers in Washington. The bulk of the spending has gone toward expensive air defense and strike munitions.

Israel and the US launched a joint attack on Iran on Feb. 28, which has so far killed over 1,300 people, including Iran's then-Supreme Leader Ayatollah Ali Khamenei, more than 150 schoolgirls, and senior military officials, according to Iranian authorities. Iran has retaliated with drone and missile strikes targeting Israeli cities and locations hosting US military assets across the region.