Arrange 2 items per row using flexbox

Imagine I have following markup

<div class="container">
    <div class="item"></div>
    <div class="item"></div>
    <div class="item"></div>
    <div class="item"></div>
</div>

and style

.item {
  width: 100%
}

and due to certain reasons I can't change the width of the .item Can I arrange 2 items in each row by styling parent container .container, using flexbox or any other way?