WASHINGTON, March 1 (Reuters) - Only one in four Americans approves of the U.S. strikes that killed Iran’s leader, while about half — including one in four Republicans — believe President Donald Trump is too willing to use military force, according to a Reuters/Ipsos poll that concluded on Sunday. Some 27% of respondents said they approved of the strikes, while 43% disapproved and 29% were not sure. About nine in 10 respondents said they had heard at least a little about the strikes, which began early on Saturday. The poll was conducted during the strikes on Iran by the U.S....