The U.S. Air Force added $13.4 billion in potential spending to an existing contract with Boeing to add foreign military sales to the scope of work.

The modification brings the total contract ceiling to $19.1 billion from $5.7 billion, the Defense Department said Friday.

Work will be performed in Seattle, and is expected to be completed by April 28, 2035.

The contract involves foreign military sales to Japan and Israel and will also include future country partners, the Defense Department said.