add_filter( 'the_content', 'facebook_sdk_replace' );
function facebook_sdk_replace( $content ) { if ( is_single() ) { $content = str_replace("/uk_UA/", "/en_US/", $content); } return $content; }

<div id="fb-root"></div>
<script>(function(d, s, id) {
  var js, fjs = d.getElementsByTagName(s)[0];
  if (d.getElementById(id)) return;
  js = d.createElement(s); js.id = id;
  js.src = "//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.6";
  fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));</script>