Russian President Vladimir Putin on Thursday welcomed his "dear friend" Chinese President Xi Jinping to the Kremlin, as they sought to strengthen ties between their two countries.

Following nearly four hours of talks, Xi said his meeting with Putin was “in-depth, friendly and fruitful,” The Guardian reported.

Putin called Xi a “dear friend” and said the talks were “warm and substantive,” adding that ties between Russia and China were stronger than ever before.

Both leaders signed a joint statement further strengthening their ties, and Putin announced that he plans to visit China in the fall for the anniversary of Japan’s defeat in World War II.

Xi is in Russia during the country's celebration of 80 years since Nazi Germany surrendered.

Russia had declared a three-day ceasefire beginning Thursday in its war with Ukraine, though both countries have claimed the other violated it.

The friendly meeting between the leaders of Russia and China comes as President Trump is pushing the former toward peace talks over Ukraine and is engaged in a trade war with the latter.

Xi said Thursday that the world was facing “unilateralism and acts of hegemonic bullying in the international arena,” appearing to refer to the U.S.'s trade war with China.