The British and Romanian governments summoned the Iranian ambassadors to London and Bucharest on Monday to protest last week's drone strike on an oil tanker in the Gulf of Oman, which both countries have attributed to Iran.

The latest: U.S. Secretary of State Antony Blinken said in a briefing Monday that the U.S. is consulting with the U.K., Romania and Israel to prepare a collective response to the alleged Iranian attack.

State of play: The Iranian foreign ministry responded to the U.K.'s move on Monday by summoning the British chargé d'affaires in Tehran, claiming the British government has no evidence to support its allegations.

• An Iranian foreign ministry official warned the British diplomat that "any adventure" by Israel or other countries will draw an Iranian response.
• In his first statement on the attack, British Prime Minister Boris Johnson called it "outrageous" and said that Iran needs to "face the consequences" for what it has done.

Why it matters: A Romanian national and a British national were killed in the July 29 attack on the Mercer Street ship, which is owned by a Japanese company but managed by Israeli-owned Zodiac Maritime. Iran is still denying its involvement.

• The U.S. and U.K. said publicly they are holding consultations regarding a possible response to the attack.

Driving the news: The Romanian foreign ministry summoned the Iranian ambassador on Monday and requested explanations from Iran without delay. "We reserve the right to act accordingly, together with our international partners, for an appropriate response," the foreign ministry said in a statement.

• The Iranian ambassador to the U.K., Mohsen Baharvand, was summoned on Monday to the Foreign Office by James Cleverly, the minister for the Middle East and North Africa.
• Cleverly reiterated in a statement that "that Iran must immediately cease actions that risk international peace and security, and reinforced that vessels must be allowed to navigate freely in accordance with international law."

The other side: An Iranian official quoted by the Nour news agency warned the U.S. and the U.K. not to threaten Iran. "Any move against the interests and national security of Iran will face a tough and firm response, and Washington and London will be directly responsible for its consequences," the Iranian official said.