That where the United States government shall acquire or has acquired, after December 7, 1941, by purchase, gift or condemnation any lands in this state for military or naval purposes and within the boundaries of the lands so acquired there are located county or township roads and some or all of such roads are closed to public travel, the closing of such roads and the closing of extensions of such roads lying outside said boundaries which connect with other township or county roads or state highways shall not be construed to be or constitute an abandonment or vacation of such roads or extensions. Whenever the United States government no longer uses the lands so acquired for military or naval purposes, the board of county commissioners or township board, as the case may be, may by resolution open said roads and extensions and no condemnation or other proceedings shall be necessary to reopen the same.