By Steve Holland

WASHINGTON, Feb 23 (Reuters) - President Donald Trump said on Thursday he wants to build up the U.S. nuclear arsenal to ensure it is at the "top of the pack," saying the United States has fallen behind in its atomic weapons capacity.

In a Reuters interview, Trump also complained about Russian deployment of a cruise missile in violation of an arms control treaty and said he would raise the issue with Russian President Vladimir Putin when and if they meet.

On another front, Trump said China could solve the national security challenge posed by North Korea "very easily if they want to," ratcheting up pressure on Beijing to exert more influence to rein in Pyongyang's increasingly bellicose actions.

Speaking from behind his desk in the Oval Office, Trump also declared himself "very angry" at North Korea's ballistic missile tests and said accelerating a missile defense system for U.S. allies Japan and South Korea was among many options available. (Reporting By Steve Holland, editing by Ross Colvin)

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