US concerned by 'deepening relationship' between Russia, N.Korea over Putin visit: White House

The US on Monday voiced concern about the "deepening relationship" between Russia and North Korea as the Russian president is due this week in Pyongyang.

"We're not concerned about the trip. What we are concerned about is the deepening relationship between these two countries, not just because of the impacts it's going to have on the Ukrainian people, because we know North Korean ballistic missiles are still being used to Ukrainian targets, but because there could be some reciprocity here that could affect security on the Korean Peninsula," John Kirby, National Security Council spokesman, told a press briefing.

"Now, we haven't seen the parameters of all that right now, but we're certainly going to be watching that very, very closely," he added.

Analysts have said Putin is seeking weapons in North Korea because parts are hard to get for Moscow due to Western sanctions.

Kirby said it is no surprise Putin "went to North Korea after his so-called election" this March and that "he was going to go on a little bit of a charm offensive here, and that's what he appears to be doing."

The Kremlin earlier said Putin will pay a two-day visit to North Korea from Tuesday at the invitation of North Korean leader Kim Jong Un. After North Korea, Putin will head to Vietnam, also on a two-day state visit.

Putin first visited North Korea in 2000, when he met with Kim Jong Un's father, Kim Jong Il. The current North Korean leader met with Putin in Russia's Far East last September.