"I don't think China is doing enough now because the problem is not resolved. So the question is, how much more must we do together to address this, short of a military solution," US National Security Advisor Lt Gen H R McMaster said at a news conference.
"So that's the kind of discussions that we will continue to have with the Chinese leadership as we work together with them -- not pressuring them -- but working with them," McMaster said.
He said it should not really be about pressuring China but about working with China in common interests.
During their talks in Florida Trump and XI agreed on a joint objective of denuclearisation of the Korean Peninsula.
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"That's a solid basis to work together on. There's a lot more to be done, however. The President has said that he will not tolerate a North Korean regime that can target the US, that can reach the US with a nuclear weapon. He just won't tolerate it," he said.
There was speculation earlier this year that North Korea was set to provoke Trump with its sixth nuclear test since 2006. However, the reclusive state has instead carried out a series of missile launches
North Korea has in 2016 carried out two nuclear tests and 20 ballistic missile tests, all in violation of international law, according to US authorities.