An ongoing blockade of Ukrainian ports by the Russian army has cut the world off from over 20 million tons of grain, kickstarting a global food crisis and accelerating famine’s spread in the world’s most vulnerable countries.

Ukrainian President Volodymyr Zelensky, European political leaders, and even the Pope have urged Russian President Vladimir Putin to lift the blockade, but their pleas have so far fallen on deaf ears, as Putin is refusing to free Ukrainian ports until the West lifts its sanctions that have been crippling Russia’s economy since the war began.

Now, as 400 million people around the world who relied on Ukrainian-produced food grow hungrier, the U.S. government is weighing in.

“This is all deliberate,” U.S. Secretary of State Antony Blinken said at a food security conference on Monday. “President Putin is stopping food from being shipped and aggressively using his propaganda machine to deflect or distort responsibility because he hopes it’ll get the world to give in to him and end the sanctions. In other words, simply put, it’s blackmail.”

Blinken cited video evidence shared by Ukrainian farmers of farmlands and agricultural infrastructure damaged by Russian forces with explosives and missile strikes. He added that the U.S. now possesses “credible reports” that the Russian military is not only blocking Ukraine’s food exports, but looting harvests and hoarding grain before selling it on global markets for a profit.

The UN was the first to report “anecdotal evidence” in early May of reports that Russian forces had been pilfering Ukrainian grain harvests in Russian-occupied portions of the country. Multiple Russian vessels have since been spotted leaving the Black Sea carrying Ukrainian grain, headed for port cities in Egypt and Syria to sell it.

U.S. government officials sent out a warning in mid-May to several nations, primarily in Africa, warning against buying looted Ukrainian grain from Russian sellers, the New York Times reported on Monday.

A global hunger crisis

But many hunger-vulnerable countries in Africa and the Middle East highly dependent on food and fertilizer imports from Russia and Ukraine may not have a choice.

In a tweet last week, Senegalese President Macky Sall said that Putin had expressed his “availability” to resume grain exports from Ukraine, and despite Western countries having yet to directly sanction the flow of food and fertilizer from Russia, called on the West to remove sanctions placed on these products.

Sall, who is also the African Union’s chairman, warned Western officials in May that the shortage of food and fertilizers is “very serious and alarming,” and cautioned that Putin’s propaganda machine blaming the West for the crisis was “out there” and starting to work in Africa. Putin met with African Union leaders last Friday to discuss food exports, a summit Sall later said had “reassured” him.

Prior to the war, Africa imported 44% of its wheat from Russia and Ukraine, according to the UN, and the supply shortage is starting to spiral toward catastrophic consequences.

On Tuesday, UNICEF, the UN child welfare agency, warned of an imminent crisis in the Horn of Africa due to hunger caused by the war and years of erratic climate conditions, with as many as 1.7 million children in need of urgent care for malnutrition.

The UN is reportedly attempting to negotiate a deal with Russia to lift the blockade of Ukrainian ports and alleviate the emergency, although it is not yet clear whether sanctions relief is on the table. The U.S. has so far appeared unwilling to discuss lifting any sanctions on Russia.