British Ambassador to the United Nations Karen Pierce echoed President Trump's message Sunday to Iran as leaders in Tehran gear up to deal with protesters responding to their government's revelation it shot down a Ukrainian passenger jet. "The important thing is that... the Iranian government needs to listen to its people and it needs to de-escalate the current situation... that's in their hands," Pierce said Sunday on "America's News HQ." Hours earlier, Trump issued warnings of his own, tweeting, "To the leaders of Iran - DO NOT KILL YOUR PROTESTERS. Thousands have already been killed or imprisoned by you, and the World is watching. More importantly, the USA is watching." To the leaders of Iran - DO NOT KILL YOUR PROTESTERS. Thousands have already been killed or imprisoned by you, and the World is watching. More importantly, the USA is watching. Turn your internet back on and let reporters roam fre...