"It is my honor as Speaker, on behalf of the bipartisan leadership of the House of Representatives and the Senate, to extend to you an invitation to address a Joint Meeting of the two houses of Congress… at 11 a.m. on Wednesday, April 3, 2019", Pelosi wrote in her letter to Stoltenberg on Monday.
Stoltenberg will be visiting Washington, DC to celebrate the 70th anniversary of the founding of the NATO alliance.
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"During this critical time for the United States, NATO and the European Union, the U.S. Congress and the American people look forward to your message of friendship and partnership, as we work together to strengthen our critical alliance and advance a future of peace around the world", Pelosi wrote in her letter.
According to the report, nations currently hosting US forces could be asked to pay five to six times as much as they do now under the so-called "Cost Plus 50" formula.
US President Donald Trump, who frequently criticizes US allies for their lack of defense spending, has championed the idea for months, the report said. Officials caution that "Cost Plus 50" is one of many ideas under consideration, and it may be toned down.
READ MORE: White House Confirms Trump Asked NATO Members to Increase Defense Spending to 4%
Despite the proposal's early stage, it has sent "shock waves" through the US departments of Defense and State, where officials fear the proposal could further alienate allies in Asia and Europe already questioning Trump's commitment to them, the report said.
According to NATO, only five out of 29 alliance members — Estonia, Greece, Latvia, the United Kingdom, and the United States — currently meet their commitment to spend 2 percent of their GDP on defense.
READ MORE: Just Over Half of NATO Members on Track to Reach Defense Spending Goal