In return for rescuing ZTE, Mr. Trump may be hoping to persuade China to drop proposed tariffs on USA agricultural and other products.
Some senior Chinese officials were enraged and have urged Trump to reverse decisions made by Commerce Secretary Wilbur Ross and others.
The timing of the president's renewed tweeting came amid criticism from both Republicans and Democrats to what seemed like an abrupt about-face on USA policy.
The sanctions were slapped on ZTE because of its business with Iran and North Korea.
Earlier this month, a USA delegation led by Treasury Secretary Steven Mnuchin presented China with a list of demands to tackle allegations of intellectual property theft and other trade policies Washington considers unfair.
The company produces telecommunications equipment that includes mobile phone handsets, servers, switches, routers, and cellular network gear.
ZTE announced last week the US sanctions would force it to curtail major operations. "The more we can work things out, the better it's going to be not just for USA and China, but for the entire world economy", he said.
Trump, who campaigned for the White House pledging to get even with China on trade practices that hurt American consumers, faced backlash from Republican and Democratic lawmakers after he promised to work with Chinese President Jinping Xi to help ZTE, saying too many jobs in China had been lost.
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Liu's trip to Washington follows a visit by Mnuchin and other US officials to Beijing earlier this month, where they conveyed a demand that China slash its trade surplus with the U.S.by $200 billion by the end of 2020. Relief for ZTE is one of China's top demands in the ongoing US-China trade skirmish.
Increasing U.S. exports of liquefied natural gas could also be an area where the two countries could agree, he said. "Given the security concerns associated with these devices, as expressed by senior USA intelligence officials, it was not prudent for the department's exchange services to continue selling these products to our personnel".
"The tariffs proposed by President Trump would cripple my business and many like it in the Midwest", according to Buchzeiger, the chief executive of the Michigan-based automotive supplier Lucerne International.
In January, the lawmakers proposed a bill that would ban the United States government from using Huawei or ZTE phones, citing a threat to national security.
A security firm, Kryptowire, disclosed in 2016 that Chinese phones are loaded with software that sends a user's data to Beijing.
"Problem with ZTE isn't jobs & trade, it's national security & espionage", Florida senator Marco Rubio tweeted.
The yield on 10-year U.S. Treasury notes rose to its highest level since July 2011 on the news, raising expectations for further rate hikes from the Federal Reserve. But most of its products rely on core technology supplies from American companies like Qualcomm and Intel. "It is because they got caught helping North Korea and helping Iran evade sanctions and they were punished for it".
"The USTR hearing will occur in the wake of President Trump's policy reversal on ZTE and an upcoming visit to DC from China's vice-premier, both of which reinforce our belief that there is still the basis and timing necessary for a broader deal", Boltansky wrote in a note to clients.