April 14 (UPI) — China on Tuesday rebuked the United States over its naval blockade of Iranian ports, calling it “dangerous and irresponsible” and warning that disregarding international law risked abandoning the world to the “law of the jungle.”

Chinese foreign ministry spokesman Guo Jiakun told a news conference in Beijing that the blockade imposed on Monday after failed U.S.-Iran peace talks over the weekend would “exacerbate tensions and undermine the already fragile ceasefire agreement.”

“This is dangerous and irresponsible behaviour”, said Guo.

Guo warned Beijing would retaliate if the United States followed through on threats to impose 50% tariffs on Chinese goods to punish it for providing air defense systems to Tehran, saying reports that China was preparing to supply the equipment were “completely fabricated.”

“If the U.S. insists on using this as an excuse to impose additional tariffs on China, China will definitely take resolute countermeasures,” Guo said.

Chinese President Xi Jinping made the law of the jungle comments in talks with Abu Dhabi Crown Prince Sheikh Khaled bin Mohamed, according to a Chinese foreign ministry readout of the meeting which took place in Beijing on Tuesday

Xi presented “four proposals” for peace and stability in the Middle East, including commitment to the “principle of peaceful coexistence” between nations and respecting national sovereignty, the ministry said.

Xi also urged steadfast adherence to international rule of law, saying it “must not be selectively applied or disregarded, nor should the world be allowed to regress to the law of the jungle.”

Iranian Ambassador to the United Nations Amir Saeid Iravani said the U.S. blockade was a breach of Iran’s sovereignty under international law and the international laws of the sea.

“The imposition of a maritime blockade constitutes a grave violation of the sovereignty and territorial integrity of the Islamic Republic of Iran. It amounts to a flagrant breach of the prohibition on the threat or use of force enshrined in Article 2(4) of the Charter of the United Nations and constitutes a clear act of aggression under international law,” he wrote in a letter to U.N. Secretary General Antonio Guterres.

“By seeking to obstruct maritime traffic to and from Iranian ports, the United States unlawfully interferes with the exercise of the sovereign rights of the Islamic Republic of Iran and infringes upon the rights of third States and lawful maritime commerce under international law,” Iravani wrote.

The criticism from Beijing and Tehran came amid reports that at least four Iran-linked ships transited the Strait of Hormuz on Monday and Tuesday, in the 20 or so hours since the blockade came into force at 10 a.m. EDT on Monday.

Two of the ships visited Iranian ports, according to MarineTraffic tracking data seen by the BBC before sailing west-to-east through the strait.

The bulk carrier Christianna sailed through the strait after calling at Bandar Iman Khomeini on the far northern shore of the Persian Gulf while the U.S.-sanctioned tanker, Elpis, transited the strait overnight from the Iranian port of Bushehr.

The U.S. sanctioned Rich Starry also transited the strait eastwards overnight from Sharjah in the United Arab Emirates.

Murlikishan, another U.S.-sanctioned tanker, transited in the other direction overnight en route from Lanshan in eastern China.

The BBC stressed that the vessels could have been faking their true coordinates by “spoofing,” where ships cover their tracks by broadcasting false position reports.