ZURICH (Reuters) -Novartis has increased its stockpiles of pharmaceuticals in the United States and is well prepared should its products be hit by President Donald Trump's tariffs, its chief executive said in an interview published on Saturday.

Pharmaceuticals are currently exempt from the 39% tariffs Washington imposed on Switzerland last month, although the industry is awaiting the outcome of a investigation which could lead to sectoral import duties.

The U.S. also reached a bilateral trade deal with the European Union in July, which includes a 15% tariff on pharmaceuticals, except for some generic drugs.

"We have significantly increased our stockpiles in the U.S., so they will certainly last until mid-2026," CEO Vas Narasimhan told Swiss newspaper Neue Zuercher Zeitung.

Novartis has already announced $23 billion in medium-term investments in the U.S. and aims to manufacture its most important products for the American market locally, he added.

"It will likely take three to four years to get there. But I estimate that we can make significant shifts within the next two years, for example, to carry out some of the final filling and packaging in the U.S.," he said.

"This should allow us to fully mitigate any tariffs."

Narasimhan said it was "difficult to estimate" whether potential tariffs of up to 250%, following Washington's Section 232 investigation into the pharma industry, were realistic.

"We're working on all possible scenarios, and hope the government realises that expanding production in the U.S. will take time," he said.

"But we won't have more clarity until the so-called Section 232 investigation is completed," he said. "We don't know when the results will be available."