The U.S. President has reportedly sent a letter to Chinese President Xi Jinping regarding the ongoing situation with Iran. The specifics of the letter's content remain unrevealed, but it is assumed to discuss the U.S.'s stance on Iran and seek China's cooperation. This move follows rising tensions in the Middle East and can potentially influence global politics concerning Iran.

Japan, having diplomatic ties with both the U.S and Iran, tends to take a delicate stance on such issues. The safety of Japanese citizens in the Middle East and the nation's energy security is of primary concern, as Iran is a significant supplier of oil. Further, Japan's close alliance with the U.S. brings about interest in any development involving American foreign policy.

In the U.S or EU, attention lies primarily on the impact this move could have on their diplomatic stand with Iran and China. Concerns may center around potential shifts in U.S policy direction, potential alliances, and geopolitical stability. Moreover, it's an opportunity to scrutinize the policies of the U.S administration.