The Confederation Congress also lacked the power to regulate foreign and interstate commerce. Britain, France and Spain imposed various restrictions on American ships and products, while the US was unable to coordinate retaliatory trade policies. When states like Massachusetts or Pennsylvania placed reciprocal duties on British trade, neighboring states such as Connecticut and Delaware established free ports to gain an economic advantage. In the 1780s, some states even began applying customs duties against the trade of neighboring states. In 1784, Congress proposed an amendment to give it powers over foreign trade; however, it failed to receive unanimous approval by the states.