HONOLULU -- President Obama told congressional leaders Sunday that he was closely monitoring the unrest in South Sudan, after four U.S. service members were attacked near Bor, and said he ldquo;may take further action to support the security of U.S. citizens, personnel and property, including our Embassy, in South Sudan.rdquo;img src="http://feeds.feedburner.com/~r/latimes/africa/~4/TTmEYvzh17U" height="1" width="1"/