The ​United States’ war in Iran has cost $29 ‌billion so far, a senior Pentagon official said on Tuesday, an increase of $4 billion from an estimate provided ​late last month.

With just six months before ​the midterm elections in which President Donald Trump’s ⁠Republicans may face an uphill battle to ​keep their House majority, Democrats are riding high ​in public opinion polls as they attempt to link the war to cost-of-living issues.

On April 29, the ​Pentagon said the war at that point ​had cost $25 billion.

Jules Hurst, who is performing the duties of ‌the ⁠comptroller, told lawmakers on Tuesday that the new cost included updated repair and replacement of equipment and operational costs.

“The joint staff team and the comptroller team are constantly looking ​at that ​estimate,” Hurst ⁠said. He was speaking alongside Defence Secretary Pete Hegseth and Chairman of ​the Joint Chiefs of Staff, General Dan ​Caine.

It ⁠is unclear how the Pentagon arrived at the $29 billion figure. A source told Reuters in March that ⁠Trump’s ​administration estimated the first six ​days of the war had cost at least $11.3 billion.