JBG Smith Properties is rolling out plans for even more new construction in Crystal City, outlining details for another mixed-use building in the shadows of Amazon.com Inc.’s new headquarters.

The Bethesda developer announced Monday it hopes to build a nine-story, 240,000-square-foot building on a vacant property at 101 12th Street S. The project would be one of JBG Smith’s northernmost efforts in National Landing, sitting not far from Long Bridge Park and Boeing’s massive facility near the Pentagon.

The company is pitching the vast majority of the building (about 235,000 square feet) as office space. The remaining 5,000 square feet would be ground-floor retail.

The proposal comes just a few weeks after JBG Smith (NYSE: JBGS) submitted plans for a half-dozen new buildings across Crystal City, designed to seize upon the arrival of thousands of Amazon (NASDAQ: AMZN) workers in the area in the coming years. However, the bulk of those plans were for residential buildings, and this…