President Donald Trump is seeking to increase the financial pressure on Iran with new secondary sanctions on nations and foreign actors propping up the regime’s economy as the war between the United States and Tehran nears the six-month mark.

Treasury Secretary Scott Bessent will announce the increased sanctions, labeled as an “economic D-Day,” on Monday. The move is meant to pressure Iran to either capitulate or begin negotiating in good faith.

A source familiar told the Washington Examiner the U.S. has “mapped Iran’s oil-smuggling and sanctions-evasion network” to ensure the secondary sanctions are as effective as possible. The Treasury Department plans to issue the sanctions in waves, with an initial list of countries targeted immediately. Countries not initially targeted by Monday’s penalties but engaging in economic activity benefiting Iran will be given time to cut ties before penalties are imposed.

The U.S. and Western countries have maintained sanctions against Iran’s energy sector and its partners for decades. Treasury officials did not specify which sectors the new sanctions would affect, but said that any business conducted with Iran could be targeted both now and in the future.

Bessent argued in an op-ed published over the weekend that the new economic pressures brought against Tehran would completely collapse the Iranian financial system, as Trump looks to conclude the war via economic, not military, means.

“President Donald Trump and the overwhelming might of our military have significantly dismantled Iran’s military capabilities and weakened its nuclear programme. Now we are entering the endgame,” he wrote in the Financial Times. “President Trump has decimated Iran’s economy to a point where the rial has never been weaker and inflation has rarely been higher. The regime’s final refuge now lies in the self-deception of fearful nations that still believe accommodating aggression can secure a durable peace.

“The world should understand that our objective is to sever every economic lifeline that sustains the tyrannical regime until Tehran stands alone,” he wrote. “As a great wave of American resolve comes ashore, are Iran’s enablers willing to wager their future against it?”