The Trump administration this morning waived the provisions of the Jones Act with respect to ports in Puerto Rico. White House press secretary Sarah Huckabee Sanders announced the change of policy in a tweet.

At @ricardorossello request, @POTUS has authorized the Jones Act be waived for Puerto Rico. It will go into effect immediately.

— Sarah Sanders (@PressSec) September 28, 2017

Trump has been under pressure from officials in Puerto Rico for days to suspend the provisions of the law in the aftermath of Hurricane Maria. It has been increasingly difficult to get emergency provisions to the island commonwealth, argued Puerto Rico’s governor and others.

The waiver allows relief supplies to be shipped to Puerto Rico on non-US vessels. The Department of Homeland Security confirmed that this waiver applies to all products. Recent waivers of the Jones Act, following Hurricanes Harvey and Irma, applied only to petroleum products.

The Washington Post reports this morning that Republican lawmakers also pressed Trump on the Jones Act waiver, after the president dragged his feet on the issue.

The waiver is good for ten days. That interval raised criticism from those who thought that was too short a period to aid in the rebuilding of the devastated island.

The Merchant Marine Act of 1920, a.k.a. the Jones Act requires that ships transiting between two United States ports fly the US flag.

The Jones Act waiver brings to the forefront the issue of whether the Jones Act should be repealed with respect to Puerto Rico or done away with altogether. Legislation that would exempt Puerto Rico from the act have been periodically introduced in the US Congress, as recently as last year.

Jones Act critics say it inflates the price of consumer goods and inhibits economic growth in states and territories not part of the contiguous 48 states. Supporters of the law say that it is necessary for national security—by ensuring a ready reserve of U.S. capacity in case of war or emergency—and creates jobs for U.S. citizens. Backers of an exemption for Puerto Rico argue that would help ease the commonwealth’s financial woes.

The Trump administration has never articulated a position on the Jones Act to date. But yesterday, President Donald Trump may have revealed some of his thinking on the matter. When asked by a reporter whether he would lift the Jones Act for Puerto Rico, he answered, “Well, we’re thinking about that, but we have a lot of shippers and a lot of people and a lot of people who work in the shipping industry that don’t want the Jones Act lifted.”