Mahan Air, a major Iranian airline, said it would stop flying to Turkey and Oman just over a week after new U.S. restrictions were announced, adding to the country’s isolation and pressure on its economy.

The measures make it difficult for other countries and non-Iranian companies to work with Iran’s aviation industry, as doing so could put them at risk of punishment by the U.S. government. Mahan Air said it would stop flights to Oman starting on Thursday and to Turkey starting on Monday. It did not explain in detail, saying only that it would stop flights after unspecified decisions by the Turkish and Omani aviation authorities.

The suspensions come as a longstanding economic crisis in Iran has been worsened by the war. The U.S. Navy has instituted a blockade of Iran’s southern ports, curtailing its ability to export oil or import key goods. Iran’s rial has fallen to new lows, making imports more expensive.

The restrictions are part of a broad U.S. campaign to cut off Iran’s ability to skirt limits on its financial and military sectors. They also could make it harder to maintain American-made planes used by Iranian airlines.