The recent seizure of an oil tanker known as Skipper by the U.S. off the coast of Venezuela marks a dramatic escalation of President Donald Trump’s campaign to choke off Venezuelan leader Nicolás Maduro’s access to oil revenues.

The oil tanker was carrying sanctioned oil from Iran and Venezuela to Cuba. Venezuelan government accused the U.S. of seeking control over their natural resources. The seizure comes as the U.S. has significantly increased military presence in the Caribbean against Venezuela.

Venezuela may soon have to start closing some oil wells as it runs low on storage capacity following last week's tanker seizure and U.S. plans to block other sanctioned vessels, Bloomberg News reported on Wednesday,

They were really close,” one of the pilots told controllers of the encounter at approximately 26,000 feet. “We were climbing right into him.”

The United States has dramatically escalated tensions in the Caribbean after federal authorities seized an oil tanker linked to Iran and Venezuela under a judicial warrant. U.S. officials say the vessel was part of a covert oil-smuggling network tied to Iran’s Islamic Revolutionary Guard Corps,

The U.S. government seized the ship off Venezuela this week for allegedly transporting oil to sanctioned Iran.

The U.S. government carried out its seizure of the M/T Skipper off the coast of Venezuela on Wednesday just as a judge-signed warrant was set to expire, according to the document which was unsealed on Friday.

The large-scale U.S. military buildup in the Caribbean suggests Trump’s pressure campaign on Maduro is expanding after the seizure of a Venezuelan oil tanker.