welcome back to our viewers in the united states, the united kingdom and across the world. you're watching "cnn newsroom." i'm bianca nobilo in london. here are the headlines this hour. american troops are massing on the u.s. border as president trump has ordered. a labor union for border patrol officers posted these photos on social media. they show u.s. troops installing barbed wire on the river and port of entry. a caravan of central american migrants, men, women and children, are traveling through mexico now to claim asylum in the u.s. iran's leaders were holding anti-american protests one day before u.s. sanctions go into effect. iran's supreme leader ayatollah c khomeini is slamming the u.s. for the sanks snor the sanks s s for the sanks sanctions.