Tokyo is preparing to arrange a summit between Prime Minister Shinzo Abe and North Korean leader Kim Jong Un in September in Russia, after Kim expressed his readiness to meet with Abe during his meeting with U.S. President Donald Trump, a government source said Thursday.

The two leaders could meet in Russia's Far Eastern city of Vladivostok on the sidelines of the Eastern Economic Forum, which Abe is expected to attend. Kim has also been invited by Russia to take part.

Russian President Vladimir Putin recently invited Kim to make his first trip to the country since taking power in late 2011, and attending the forum, which is scheduled for Sept. 11-13, could be one opportunity.