UPDATE 1-NATO's Stoltenberg will be invited to address U.S. Congress -source

U.S. House of Representatives Speaker Nancy Pelosi plans to invite NATO Secretary-General Jens Stoltenberg to address a joint meeting of Congress in April, as the alliance celebrates its 70th anniversary, a source familiar with the situation said on Monday.

The invitation, which comes after President Donald Trump has questioned NATO's value to Washington, is supported by the other leaders of Congress, both Republicans and Democrats, the source said. In February, Pelosi led a 50-member delegation of U.S. lawmakers to Brussels, where they sought to reassure European allies that differences over Trump's policies were mere "family squabbles" and that transatlantic ties remained strong.

Pelosi met with NATO's leadership during that visit. The European Union and United States have traditionally been the closest of allies, also working together through NATO.

Trump, however, has lambasted his European peers for not spending enough on defense, raising doubts among many in Europe about his commitment to the Western military alliance and Europe's broader security. (Reporting by Patricia Zengerle; Editing by Peter Cooney)