Nippon Steel and U.S. Steel sued the U.S. government Monday for blocking the merger of the two companies on national security grounds.

The suit, filed in the U.S. Court of Appeals for the District of Columbia Circuit, challenges the decision by President Joe Biden to reject the deal, arguing that the companies were denied due process and other rights and claiming that the $14.9 billion transaction was blocked for political reasons.

Determinations by the Committee on Foreign Investment in the United States (CFIUS) and subsequent national security decisions by presidents based on those determinations are generally not subject to judicial review, but some success has been achieved with claims involving questions about due process and procedural matters.

The suit filed Monday by the two companies seeks to have the CFIUS review of their deal set aside and a new review conducted.

"We firmly believe that the various facts that will come to light through the litigation will demonstrate that this decision clearly violated the Constitution and laws," Nippon Steel Chief Executive Eiji Hashimoto said during a news conference Tuesday morning.

“There is no reason or need to give up,” he added. “I am convinced that this is the best course of action.”

A second suit, filed by the two companies in the U.S. District Court for the Western District of Pennsylvania, alleges that Cleveland-Cliffs, Cleveland-Cliffs CEO Lourenco Goncalves and David McCall, president of the United Steelworkers, engaged in “illegal and coordinated actions” aimed at preventing the deal.

The suit seeks monetary damages and an injunction against the defendants from “engaging in collusive and anti-competitive behavior.”

Biden announced Friday his decision to block the transaction due to national security concerns, saying the proposed deal would endanger America’s steel supply, after CFIUS failed to achieve a consensus in a monthslong review.

The two companies said they are committed to closing the transaction despite “racketeering and monopolistic conspiracies” involving Cleveland-Cliffs and McCall.

“We remain confident that the transaction is the best path forward to secure the future of U.S. Steel — and we will vigorously defend our rights to achieve this objective,” the two companies said in a statement.

Having been mostly silent since the proposed transaction was announced over a year ago, some government officials in Tokyo voiced concerns following Biden’s Friday decision. Prime Minister Shigeru Ishiba said earlier on Monday that the U.S. needs to address concerns that are critically important to the future of Japan-U.S. relations.

"It is an unfortunate fact that concerns are being raised within Japan's industrial sector. We cannot take this lightly," Ishiba said. "Conversations won’t go forward without a clear explanation as to why there are security concerns. No matter how strong our alliance, this matter is critically important for the future of our relationship."

Industry minister Yoji Muto also said on Monday that the government needs to consider specifically what kind of support it can provide to Nippon Steel.

Foreign Minister Takeshi Iwaya and U.S. Secretary of State Antony Blinken are set to meet in Tokyo on Tuesday.