U.S. President Donald Trump and Israeli Prime Minister Benjamin Netanyahu spoke on the phone Wednesday about Iran, in addition to joint American-Israeli security interests, as Trump threatened that U.S. sanctions on Iran will be “increased substantially” in response to the regime last week exceeding the uranium-enrichment limit under the 2015 nuclear deal.

“The two leaders discussed cooperation between the United States and Israel in advancing shared national-security interests, including efforts to prevent Iran’s malign actions in the region,” White House spokesperson Judd Deere told reporters on Thursday.

“I spoke with U.S. President Donald Trump. We discussed regional developments and security issues. Foremost among them was Iran. I thanked President Trump for his intention to increase sanctions against Iran,” tweeted Netanyahu on Thursday.

The two spoke as three Iranian Islamic Revolutionary Guard Corps vessels “attempted to impede” a British oil tanker in the Persian Gulf on Wednesday, according to a statement by the British government.

Iran has denied attempting to stop the British vessel.

The U.S. State Department condemned the IRGC.

“We are aware of reports that Iranian boats attempted to seize a British oil tanker,” a department spokesperson told JNS. “The United States will continue to work with our allies and partners to address the Iranian regime’s corrupt and malign activities, and to safeguard global commerce.”

The incident occurred a week after the Iranian oil tanker Grace 1 was seized by the United Kingdom off the coast of Gibraltar on suspicion of transporting oil to Syria in violation of E.U. sanctions.

Chief of Staff for the Armed Forces of the Islamic Republic of Iran Maj. Gen. Mohammad Bagheri said the seizure was “based on “fabricated excuses,” and warned that it “will not be unanswered, and when necessary, Tehran will give the appropriate answer.”