Among the potential changes mentioned is that the USA may not defend another member country if it does not meet the defense alliance's goal of annual investments in defense or the level Trump considers sufficient.
The President is also considering a policy change where the USA can choose to prioritize military exercises with NATO countries that meet the goal, and to redeploy some of the American forces in Europe to or around those countries, according to sources.
The information comes in the wake of the latest weeks' signals from the USA that the country may reduce its military presence in Europe in the future.
Trump has repeatedly criticized NATO countries that do not meet the current goal of allocating two percent of their GDP to defense, and demanded that countries increase their defense expenditures to five percent of GDP.
The question of a potential increase in the expenditure target is expected to be one of the points on the NATO summit in The Hague at the end of June.
