<p>WASHINGTON (AP) -- The <a href="http://topics.nytimes.com/top/reference/timestopics/organizations/i/interior_department/index.html?inline=nyt-org" title="More articles about Interior Department, U.S.">Interior Department</a> declared the polar bear a threatened species Wednesday, saying it must be protected because of the decline in Arctic sea ice from <a href="http://topics.nytimes.com/top/news/science/topics/globalwarming/index.html?inline=nyt-classifier" title="Recent and archival news about global warming.">global warming</a>.</p><p>Interior Secretary <a href="http://topics.nytimes.com/top/reference/timestopics/people/k/dirk_kempthorne/index.html?inline=nyt-per" title="More articles about Dirk Kempthorne.">Dirk Kempthorne</a> cited dramatic declines in sea ice over the last three decades and projections of continued losses. These declines, he told a news conference, mean the polar bear is a species likely to be in danger of extinction in the near future.</p>