WASHINGTON (AP) -- President Donald Trump met with his Ukrainian counterpart Tuesday amid intensifying questions over whether his administration will step in to protect partners in the face of Russian aggression.

The meeting with Ukrainian President Petro Poroshenko was originally described by the White House as a brief "drop-in." But the two presidents posed for photographs in the Oval Office and made brief remarks following Poroshenko's more extensive meetings with Vice President Mike Pence and the administration's top national security advisers.