By Dietrich Knauth, Blake Brittain NEW YORK (Reuters) -Five American small businesses asked a U.S. court on Tuesday to halt President Donald Trump's "Liberation Day" tariffs, arguing that he overstepped his powers by declaring a national emergency to impose across-the-board taxes on imports from nations that sell more to the United States than they buy.

Long-threatened tariffs from U.S. President Donald Trump have plunged the country into trade wars abroad — all while on-again, off-again new levies continue to escalate uncertainty. Trump launched a trade war during his first term as well,