Santander Bank has notified regulators that it plans to close about 4.5% of its U.S. branch network this summer, with all of the shutdowns slated to affect locations in the Northeast.

The U.S. subsidiary of Spanish banking giant Banco Santander filed 18 advance branch closing notices last week with the Office of the Comptroller of the Currency. Of the 18 offices, six are in Massachusetts, four are in New Jersey and another four are in Pennsylvania. Two offices are in the New York metro area and the remaining two are in Rhode Island and New Hampshire.

News of the U.S. closures comes about seven weeks after Santander said it would shut down 95 of its 444 branches in the United Kingdom this summer. That's about one-fifth of its total U.K. branch network. The bank also said it would reduce operating hours at 36 other U.K. offices.

The U.S. closures, which are expected to happen between July 31 and Aug. 21, come as Santander pursues a nationwide digital banking strategy in the United States. In October, it launched Openbank , an online banking platform, to attract deposits from across the country.

The product kicked off with a high-yield savings account offering a premium interest rate, and there are plans to offer a checking account and certificates of deposits by the end of the year.