WASHINGTON, Sept 23 (Reuters) - German Defense Minister Annegret Kramp-Karrenbauer on Monday said she aimed to decide as soon as possible next year how to replace Germany’s aging fleet of Tornado fighter jets to prevent a lapse in Germany’s ability to carry out missions for NATO.

Kramp-Karrenbauer, leader of Chancellor Angela Merkel’s Christian Democrats, said she discussed the issue with U.S. Defense Secretary Mark Esper during her first official visit to Washington since taking on her new role as defense minister.

Germany in January decided to pick either the Eurofighter - built by Airbus, Britain’s BAE Systems and Italy’s Leonardo SpA - or Boeing Co’s F/A-18 fighter, dropping Lockheed Martin’s F-35 fighter out of a tender worth billions of euros.

However neither the F/A-18 nor the Eurofighter is currently certified to carry U.S. nuclear weapons, as required under Germany’s obligations to NATO. Germany is asking Washington to spell out what it will take to get those aircraft certified.

“My goal is that we make clear decisions as quickly as possible next year, so there is no time period in which there is no reasonable solution for replacing the Tornado fleet,” Kramp-Karrenbauer told reporters.

She said she would work closely with Esper on the issue in coming months. But experts say it could take years to get the new planes certified to carry nuclear weapons, and the cost of maintaining the current aircraft is rising rapidly.

Kramp-Karrenbauer said she also had a frank discussion with Esper about Germany’s rejection of the F-35 as a possible replacement for the Tornado jets, given concerns that it could impede work on a Franco-German next-generation combat jet.

“We made clear that ... the Future Combat Air System with the French was one of the reasons that ... we had to seek other solutions,” she said, when asked if she ruled out taking another look at the F-35.

Lockheed officials had hoped that Germany could reconsider its decision after the departure of former Defence Minister Ursula von der Leyen.

The German defense ministry in April estimated it would cost nearly 9 billion euros to keep its 93 Tornado jets, which first entered service in 1983, flying until 2030.

Of Germany’s Tornado jets, 85 are operated by the Luftwaffe, or air force but not all are equipped to carry nuclear weapons. The remaining planes are used for training. (Reporting by Andrea Shalal; Editing by Cynthia Osterman)