Washington (CNN) US national security adviser John Bolton on Friday shared a satellite image of an Iranian tanker off the coast of Syria, after the Iranian government denied that it was the vessel's final destination.

The Iranian tanker— Adrian Darya 1, formerly known as the Grace 1 — was seized in July by the UK in Gibraltar, due to evidence that the vessel was attempting to carry oil to Syria in violation of European Union sanctions against Syrian President Bashar al-Assad's regime.

"Anyone who said the Adrian Darya-1 wasn't headed to Syria is in denial," Bolton wrote on Twitter, along with a satellite picture from DigitalGlobe timestamped September 6 showing the tanker two nautical miles away from the Tartus Naval Base in Syria.

"Tehran thinks it's more important to fund the murderous Assad regime than provide for its own people. We can talk, but Iran's not getting any sanctions relief until it stops lying and spreading terror," Bolton added.

Anyone who said the Adrian Darya-1 wasn't headed to #Syria is in denial. Tehran thinks it's more important to fund the murderous Assad regime than provide for its own people. We can talk, but #Iran's not getting any sanctions relief until it stops lying and spreading terror! pic.twitter.com/saar05T8wt — John Bolton (@AmbJohnBolton) September 6, 2019

There have been heightened tensions between Washington and Tehran since President Donald Trump withdrew the US out of the Iran nuclear deal in 2018, and later reimposed all sanctions lifted under the 2015 agreement. This week, the Trump administration further ratcheted up pressure on Iran, announcing a reward program to disrupt Tehran's financial operations as well as confirming it had offered to pay tanker captains if they helped the United States impound Iranian vessels carrying Iranian oil and unveiling a new wave of sanctions.