Pakistan's foreign exchange reserves have crossed a historic level of USD 18 billion despite growing economic challenges. Prime Minister Syed Yousuf Raza Gilani in a statement on Thursday said that the USD 18 billion mark is a record level in the country's history. This achievement, he said, has come about despite major economic challenges like last year's devastating floods, abnormally escalating prices of fuel in the international market and global recession. The Premier also said that the reserves' mark is an evidence of the sound economic strategy of the government.