The blocking of Nippon Steel’s acquisition of United States Steel by a U.S. president was the consequence of significant “political interference” and was difficult to understand, the Japanese prime minister told parliament on Monday.

Prime Minister Shigeru Ishiba made the comment during a Lower House budget committee meeting that day. Tadashi Morishima, a Nippon Ishin no Kai lawmaker, asked Ishiba what he thought of the decision by then-U.S. President Joe Biden to reject the deal on national security grounds.

It was the result of “unjust political interference. This is why we objected to this matter and told them that we find it difficult to understand,” Ishiba said.

Nippon Steel announced its plan to purchase U.S. Steel in late 2023 in a $14.9 billion transaction. Biden blocked the deal on Jan. 3, saying it was a threat to national security.

U.S. President Donald Trump has sent mixed signals on the transaction, but has generally been against the full acquisition. He has increasingly been in favor of a minority investment by Nippon Steel into the iconic Pittsburgh-based steelmaker, but he has provided no real details on how that would be structured.

Ishiba has generally indicated support for some new arrangement that falls short of ownership. He said following a summit with Trump in the United States that U.S. Steel should remain American, although he has raised the question of the difference between investment and ownership.

Japanese government officials have also suggested that a new deal of some sort might be in the works. No details have been provided. The comments have signaled a significant reworking of the deal, but they have fallen short of indicating an acceptance of a minority ownership stake.

The position of Nippon Steel remains unclear. It has not made a public comment since just before Trump and Ishiba signaled that a full acquisition is not going to be possible. Press reports indicate that Nippon Steel wants to set up a meeting with Trump to discuss the deal. No meeting has been confirmed.

Last Thursday, TV Tokyo reported that Nippon Steel is still intent on a full acquisition of U.S. Steel and will not be satisfied with a minority position in the company.

The Japanese steelmaker filed suit against the U.S. government for blocking the transaction. Attorneys with experience in the area believe that the case is a longshot and unlikely to reverse Biden’s decision.

In January, Biden and Ishiba held a virtual meeting before Trump returned to the White House. The prime minister urged Biden to reconsider the rejection of the deal, but the Biden administration did not respond, Ishiba said.

The prime minister indicated that the situation has improved under the Trump administration, saying that there has been “a significant shift in thinking,” as Trump has said he would accept investment rather than a full purchase.

Morishima, a former Nippon Steel worker, pointed out that such a shift is a setback for Nippon Steel, as the company’s business strategy in the United States would be significantly affected if the purchase is not realized.

“We discussed that the deal should benefit both companies,” Ishiba said, recalling his conversation with Trump during the summit. “I don’t believe this situation is a setback.”

Ishiba said that the shareholding percentage will be discussed between the two companies, while Trump has said no one can take a majority stake in U.S. Steel. The prime minister added that when he met Trump, the president seemed quite adamant about U.S. Steel remaining an American company.

“If I had immediately rejected that from the outset, the negotiation would have just fallen apart, so I decided not to do so,” Ishiba said.