The talks aimed at reaching a ‘phase one’ trade deal between the U.S. and China have hit a “snag” over Chinese purchases of U.S. agricultural goods, the Wall Street Journal reported Wednesday.

President Donald Trump has said China already agreed to buy up to $50 billion in farm products from the U.S. as part of the phase one trade deal. But China is hesitant to commit to a specific amount and wants any agreement on purchases to be contingent on on-going progress of trade talks, the Wall Street Journal reported, citing unnamed sources familiar with the talks.

“We can always stop the purchases if things get worse again,” the Journal quotes one Chinese official as saying.

Beijing wants to avoid appearing to accept a deal that looks like too much of a win for the U.S., according to the report.

China has also resisted making firm commitments over protection for American intellectual and the end of forced technology transfers. In addition, it is demanding the roll-back of existing U.S. tariffs as part of any phase one deal.

U.S. Trade Representative Robert Lighthizer has fought back against lifting any of the existing tariffs without firmer commitments from China.