Mr Turnbull and Mr Trump are in Manila for the ASEAN Summit, and fronted media together with Japanese Prime Minister Shinzo Abe on Monday.
The rogue state previously threatened to launch ballistic missiles toward Guam, where a USA military base is located, prompting American President Donald Trump to declare that he would meet any threat to his country with "fire and fury."Japan and South Korea, East Asian countries that also host U.S. military installations, are also bracing for possible missile attacks".
During the meeting of two leaders in Japan in October, Abe said during the meeting that Japan will provide coastal surveillance radars to ensure effectiveness of Japan-made patrol vessels the Philippines ordered for PCG.
Abe's unprecedented meeting with both Xi and Li in such a short period of time is a sign of improving relations.
He suggested the two countries promote regional economic integration, and push for cooperation within the framework of the Belt and Road Initiative at an early date.
Abe, whose country is separated from North Korea only by the Sea of Japan, called the North Korea's nuclear and missile threat a "grave and imminent threat that we have never experienced".
Abe appealed to Li for China - North Korea's primary diplomatic and economic backer - to play a "more constructive" role, the spokesman said.
Both Japan and China have poured money and attention in recent years into the strategically important Mekong region, which includes less economically developed members of ASEAN.
Abe extended his congratulations on the success of the 19th National Congress of the Communist Party of China (CPC), which was held last month, and on Xi's re-election as general secretary of the CPC Central Committee.
This year is the 45th anniversary of the normalization of ties between Japan and China, while next year will mark 40 years since the signing of a bilateral peace and friendship treaty. "To improve China-Japan ties, the key is mutual trust".
The countries remain at odds over the Japan-controlled, China-claimed Senkaku Islands in the East China Sea, which are also claimed by Taiwan.