White House and State Department officials have told U.S. oil executives in recent weeks that they would need to return to Venezuela quickly and invest significant capital in the country to revive the damaged oil industry if they wanted compensation for assets expropriated by Venezuela two decades ago, according to two people familiar with the outreach.

In the 2000s, Venezuela expropriated the assets of some international oil companies that declined to give state-run oil company PDVSA increased operational control, as demanded by late Venezuelan President Hugo Chavez. 

U.S. oil major Chevron was among companies that negotiated to stay in the country and form joint ventures with state-run PDVSA, while rivals Exxon Mobil and ConocoPhillips left and filed for arbitration. 

President Donald Trump said on Saturday that American companies were prepared to return to Venezuela and spend billions to reactivate the struggling oil sector, just hours after President Nicolás Maduro was captured and removed by U.S. forces.

In the recent U.S. administration discussions with oil executives in the scenario that Maduro was out of power, officials have said that U.S. oil companies would need to front the investment money themselves to rebuild Venezuela’s oil industry. That would be one of the preconditions for them eventually recovering debts from the expropriations.

That would be a costly investment for firms such as ConocoPhillips, the sources said. Conoco for years has tried to recover some $12 billion from the Chavez-era nationalization of its Venezuela assets. Exxon Mobil also filed international arbitration cases, trying to recover $1.65 billion.

Trump began making public reference to the Venezuelan expropriations when he ordered a blockade of sanctioned oil tankers last month.

Whether or not the companies return would depend on how executives, boards and shareholders evaluate the risk of renewed investment in Venezuela, the sources said.

“ConocoPhillips is monitoring developments in Venezuela and their potential implications for global energy supply and stability. It would be premature to speculate on any future business activities or investments,” a company spokesperson said in emailed comments to Reuters on Saturday. The company reiterated the statement on Sunday when asked about discussions with administration officials for this story.

Exxon did not immediately respond to questions from Reuters.

Politico first reported on the recent discussions on Saturday.

Even if companies do agree to return to the country, it could be years before there is a meaningful boost to oil output. The South American country has one of the largest estimated reserves in the world, but production has plummeted over past decades amid mismanagement, lack of investment and U.S. sanctions.

Besides uncertainty surrounding the contract framework for any operations there, companies considering a return would also need to deal with security concerns, poor infrastructure, questions about the legality of the U.S. operation to capture Maduro and the possibility of long-term political instability, analysts have told Reuters. 

Venezuela, a founding member of OPEC, produced as much as 3.5 million barrels per day in the 1970s, which at the time represented over 7% of global oil output. Production fell below 2 million bpd during the 2010s and averaged around 1.1 million bpd last year, or just 1% of global production.