SEOUL, South Korea — The streets of Pyongyang, North Korea, were lined with flags and portraits Wednesday — not for Kim Jong Un, but for his guest and growing ally, Vladimir Putin.

The Russian president is meeting with the North Korean leader in a rare visit to the reclusive state, as he seeks ammunition for his war in Ukraine and vows to back the nuclear-armed regime against the United States.

U.S. officials previously told NBC News that they expect the pair to solidify a new deal to…