Is Poloniex legal in US?

Can you please clarify if Poloniex, a popular cryptocurrency exchange platform, is operating legally within the United States? Are there any legal restrictions or regulations that the platform needs to adhere to in order to continue serving US-based users? Furthermore, is it safe for US residents to use Poloniex for trading cryptocurrencies, given the potential risks and uncertainties associated with the market? I'm particularly interested in understanding the current legal status of Poloniex in the US, as well as any potential legal consequences for using the platform if it's not fully compliant with local laws.