Just one in three Americans support the war on Iran, the lowest reading in a Reuters/Ipsos poll since the five-month-old conflict's early days, with most respondents saying that President Donald Trump has failed to explain his goals.

The poll, conducted Friday through Sunday, also showed the Republican president's approval rating ticking higher to 37 percent, up three points from last month when his rating tied the lowest of his presidency.

The poll found that 69 percent of Americans, including four in 10 Republicans, think Trump has not "clearly explained the goals of US military involvement in Iran."

Approval of the conflict has been below 40 percent since the US and Israel launched strikes on 28 February - a stark contrast to the opening months of other recent conflicts.

While each had different context, the Iraq War from 2003 to 2011 had the support of about 70 percent of Americans in its early months. During the early days of the Afghanistan War, which lasted from 2001 to 2021, about 90 percent of the country backed the war, according to polling by Gallup.