Oil prices moved lower on Friday, putting Brent and West Texas Intermediate on course to end two consecutive weeks of gains as markets continued to assess developments involving the United States and Iran.

Brent crude futures fell 60 cents, or 0.67%, to $89.10 per barrel at 0636 GMT. WTI futures declined 64 cents, or 0.77%, to $82.89.

For the week, Brent was heading for a 5.3% decline, while WTI was on track to fall 4.3%.

Strait of Hormuz oil shipments show signs of increasing

Oil markets continued to monitor shipping activity through the Strait of Hormuz alongside diplomatic developments involving Washington and Tehran.

“Despite diplomatic efforts hitting a roadblock, there are growing signs of additional oil flowing through the Strait of Hormuz,” ING analysts said in a note. “As the conflict persists, producers are adapting to the new realities and becoming increasingly comfortable navigating the strait.”

Goldman Sachs estimated on Thursday that total Gulf exports had recently reached between 15 million and 16 million barrels per day.

The estimate remained 7 million to 8 million barrels per day below pre-war levels but represented an increase of between 5 million and 6 million barrels per day from the low reached in March.

Trump administration reportedly rejects return to June agreement

Crude prices had settled higher on Thursday after The Wall Street Journal reported that the Trump administration was not seeking a return to the terms of a June memorandum of understanding with Iran.

Citing people familiar with the matter, the report said the U.S. administration had repeatedly informed mediators that it had no interest in reviving the agreement, creating an additional complication for diplomatic efforts to resume negotiations.

Washington separately said earlier on Thursday that it was not holding talks with Iran, despite attempts by other countries to facilitate renewed discussions.

Washington announces additional sanctions against Tehran

The United States announced further measures against Iran on Monday, describing them as the “toughest sanctions in history”.

Iran responded by describing the sanctions as an “inhumane and hostile act” and saying that they had lost their effectiveness.

Those descriptions represent statements from the respective governments rather than independent assessments of the measures.

Russia warns of possible response involving British military targets

Separate geopolitical developments also remained under consideration after Moscow issued a warning concerning Ukrainian attacks on Russian territory using British-supplied long-range cruise missiles.

Russia said it could respond by striking British military targets both inside and outside Ukraine.

U.S. President Donald Trump, however, said Russian President Vladimir Putin would not attack a member of the North Atlantic Treaty Organization.

Trump also played down media reports that CIA Director John Ratcliffe had warned Russian officials this week against carrying out such an attack.

Britain is a founding member of NATO.