DUBAI (Reuters) - The United States could impose sanctions on Egypt and block it from future military sales if it goes ahead with a purchase of Russian warplanes, a U.S. official said on Monday.

Egypt earlier this year signed a $2 billion agreement with Russia to buy more than 20 Su-35 fighter jets.

“It puts them at risk of sanctions and it puts them at risk of loss of future acquisitions. It’s not a new thing,” Assistant Secretary of State for Political-Military Affairs R. Clarke Cooper told reporters at the Dubai Airshow.

“Cairo is clearly aware of this. Its not new news.”

Washington could impose sanctions under its Countering America’s Adversaries Through Sanctions Act (CAATSA), which targets purchases of military equipment from Russia.

The Egyptian government could not immediately be reached for comment.

The United States has over the years provided billions of dollars in economic and military aid to Egypt, a long-time ally whose military operates the F-16 fighter jet.

Cooper said using the Su-35 and other Russian weapons systems could pose a threat to a country’s ability to operate jointly with the militaries of the United States and other NATO countries.

U.S-ally and NATO member Turkey was this year pulled from the F-35 warplane programme by Washington after Ankara went ahead with a deal for the Russian S-400 air defence system.

However, President Donald Trump has stopped short of imposing sanctions on Turkey under CAATSA.

Trump told Turkey’s President Tayyip Erdogan last week that for Ankara and Washington to maintain their relationship, the system would either need to be destroyed, compartmentalized or returned to Russia, Cooper said.

“Turkey still remains in the cold on the F-35 programme,” he said.

Other U.S allies in the region are also exploring major Russian purchases, including Saudi Arabia and Qatar, which have both expressed interest in the S-400, and the United Arab Emirates which signed an outline agreement for the Su-35 in 2017.