President-elect Donald Trump's tax cuts and spending plans could deliver a shot in the arm to the U.S. economy, lifting growth around the world, although uncertainty about his trade policies adds to the risks, according to the World Bank.

The Trump administration could squander the economic gains of fiscal stimulus if it imposes new trade barriers that provoke retaliation by other countries, the Washington-based development lender said Tuesday in the latest update to its global economic outlook.

Overall, it's too early to assess what the net impact will be of Trump's economic policies, the World Bank said. Accordingly, it left its forecast for U.S. growth this year and next unchanged, at 2.2 percent and 2.1 percent, respectively. The outlook doesn't incorporate the expected effect of Trump's policy proposals, according to the report.