It looks like Brand USA’s stated goal of bringing 100 million inbound tourism arrivals to the U.S. in 2021 may not happen given a variety of global factors.

Brand USA quietly released its fiscal year 2015 annual report earlier this month, and on the organization’s quarterly board call its executives wrestled with the realization that tourism isn’t increasing quite as quickly as they had anticipated.

In order to play catch up, Brand USA has raised its target compound annual growth rate for inbound tourism from 4.2 percent to 4.8 percent from 2016 to 2021.

“We are significantly under where we need to be for that target [of 100 million visitors by 2021],” said Caroll Rheem, Brand USA’s vice president of research and analytics, on the June 9 Brand USA conference call. “The leading driver of our underperformance is the 10 percent decline in Canadian volume.”

Financially, Brand USA reported strong support from industry partners and said its marketing efforts have been successful on a global basis in terms of driving interest in leisure travel to the U.S.

Here are four slides from Brand USA’s latest board of directors presentation that illustrate the challenges its current model faces in reaching its goals of attracting 100 million travelers to the U.S. in 2021.

Tourist arrivals were flat from 2014 to 2015

Arrivals to the U.S. didn’t grow as expected from FY2014 to FY2015, ending up basically flat, according to the latest forecast data from the National Travel and Tourism Office (NTTO).

The last time inbound tourism was flat or down was in 2009, as the Great Recession crushed global tourism demand.

The NTTO estimates now have inbound tourism six or seven million visitors shy of the 100 million mark in 2021.

“We have to make our dollars work harder than they ever had before,” said Rheem.