Washington CNN  — 

Agriculture Secretary Sonny Perdue acknowledged this week that farmers are getting hurt by President Donald Trump’s trade war, but expressed optimism that a deal would be struck with China by the end of the year.

American farmers “are one of the casualties here with trade disruption,” Perdue told CNN’s Vanessa Yurkevich in an exclusive interview.

“We knew going in that when you flew the penalty flag on China, the retaliation, if it came, would be against the farmer,” he added.

US soybean, corn, and wheat growers have been battling tariffs from China for nearly a year now. Beijing imposed those duties in retaliation to tariffs put on Chinese products by the Trump administration.

The tariffs made those American agricultural products more expensive for Chinese importers, and private buyers have mostly stopped buying American-grown soybeans or wheat.

Many farmers stood behind Trump’s mission to get a better trade deal with Beijing that addresses longstanding issues with what they say are unfair trading practices.

But some farmers started to grow impatient after Trump escalated tariffs on $200 billion of Chinese goods last month, signaling the two countries weren’t as close to striking a deal as some had expected. The news sent commodity prices plummeting.

To help farmers deal with the loss of an export market in the short-run, the Trump administration has pledged $28 billion in aid. Most of the money will be paid directly to farmers hurt by the retaliatory tariffs.

“I’ve told the President – and the President understands – you can’t pay the bills with patriotism. We know that, and certainly he knows that. That’s why he’s trying to supplement the damage they’re having from trade disruptions with market facilitation,” Perdue said.

The latest round of aid was announced in May and payments are expected to start going out this summer. But Perdue indicated that farmers should not expect additional money next year.

“I’m not going to promise anything for 2020,” he said.

Trump is expected to sit down with China President Xi Jinping at the G20 meeting in Osaka beginning on Thursday. While Perdue isn’t hopeful that the two will come to a deal this week, he’s optimistic that a deal will be struck by the end of the year.

“I believe President Xi – the relationship that he and President Trump have – I think a deal can be made and it may be done quickly,” he said.