BEIJING (AP) -- China praised U.S. President Donald Trump on Thursday for expressing a desire for a "constructive relationship" in a letter to Chinese President Xi Jinping, even though the leaders have not spoken directly since Trump's inauguration.

Trump sent belated well-wishes for the Lunar New Year in a letter from the White House on Wednesday.

He had been the only U.S. president in recent years not to have issued greetings to the world's most populous nation on its most important holiday, which fell this year on Jan. 28. The silence triggered speculation in China as to whether it was an oversight or an intentional slight.

A statement from the White House late Wednesday said Trump wrote to Xi that he looked forward to "develop a constructive relationship that benefits both the United States and China."

Foreign Ministry spokesman Lu Kang said China "highly commended" Trump for the letter to Xi wishing the Chinese people greetings for the new year and the Lantern Festival that falls on Saturday. Lu dismissed suggestions that Beijing took offense in the timing.

"It is known to all that since President Trump took office, China and the U.S. have been in close contact," Lu said.

Speculation has simmered in China about how Trump might back up his tough talk, with observers noting that since his Jan. 20 inauguration, Trump has spoken to more than a dozen foreign leaders but not Xi.

Trump has accused Beijing of unfair trade practices and a deliberately undervalued currency, criticized China's military buildup in the South China Sea and accused Beijing of doing too little to pressure neighbor North Korea over its nuclear and missile programs.

He also upended four decades of diplomatic protocol by speaking by phone with Tsai Ing-wen, the president of Taiwan, which China claims as its own territory.

Beijing decried the phone call with Tsai and has rejected the other accusations. China has in fact been spending heavily from its foreign currency reserves to prop up the value of its currency, which would make its exports less competitive.

The prospect of a military confrontation over the South China Sea has been raised by Trump's chief strategist, Steve Bannon, when he hosted the conservative Breitbart News Daily radio show in 2015 and 2016.

Bannon said he envisioned the possibility of a U.S.-China war over the strategic waterbody within five to 10 years. China, which claims virtually all of the sea, has been building man-made islands in the area and equipping them with airstrips and military installations.

Despite Trump's confrontational image, Chinese internet users were warmed by a brief video clip of his granddaughter singing in Chinese that circulated on the web earlier this month.