India will pause plans to buy weapons and aircrafts from the U.S. in response to President Donald Trump raising tariffs on Indian imports to 50%, according to Reuters. The relationship between the U.S. and India has turned sour with Trump increasing tariffs as India continues to buy cheap, sanctioned Russian oil.

For more on this, “Marketplace Morning Report” host David Brancaccio spoke with Eswar Prasad, who teaches international trade policy at Cornell University. The following is an edited transcript of the conversation.

David Brancaccio: There have been global sanctions on countries, and they're bound not to buy Russian oil. India kept buying?

Eswar Prasad: That's right. India is a pretty big importer of oil. It has a reasonably large industrial sector and needs a lot of energy that it doesn't produce on its own, and India has tried to straddle the fence between the emerging market economies, like China and Russia on the one side and the U.S. on the other side. And at least until Trump came along, it seemed to be doing so without any significant cost. The Biden administration knew that India was buying a lot of Russian oil, tried to dissuade India from doing so, but didn't really penalize India in any significant way.

Brancaccio: Would you say, in the complex game of international relations, there was an argument that the U.S. wanted to avoid getting into it with India, so that maybe India would side with the U.S. against China in the longer term?

Prasad: That's right. Geopolitics is an important part of the equation here. So India is a pretty big economy. It's now the fifth-largest economy in the world. So both the U.S. and China are trying to get India onto their side. And I think the Biden administration calculus was that it was much more important to keep India as a geopolitical ally on the U.S. side. That calculus seems to have shifted now for a variety of reasons.

Brancaccio: It's a conundrum for India. You can just imagine the analysis that they're trying to do — the cost of lost exports caused by big U.S. tariffs, versus paying for more expensive oil from sources that are not Russia.

Prasad: It's a really tough calculus for India, because India imports a lot of oil, and by buying cheap Russian oil, it keeps down domestic inflation. But India is also trying to become a more important exporting country. So it has tried to build up its industrial sector. And, in fact, some American companies like Apple had started shifting at least part of their production bases and supply chains to India. All of that is going to be hurt by these tariffs.

Brancaccio: Here I was thinking President Trump and India's Prime Minister Narendra Modi were buddies, or, at least, more closely aligned. That relationship seems to have been torn asunder here.

Prasad: It certainly looked like a budding bromance between the two leaders, it looked like that relationship was continuing. And, in fact, until very recently, all prospects were that that relationship between the two leaders and the negotiations between the two sides would result in a trade deal. The one thing that the U.S. wanted, which India was not willing to concede, was greater access to Indian markets for U.S. agricultural exports. And the second issue, of course, is that Trump seems to be taking a harder line on Russia, and India gets caught in the crossfire.