"It's only when you get up at 2:00 am to answer the call of nature that you can fully appreciate how a US aircraft carrier operates around the clock," writes John Hadoulis, a correspondent based in Athens, after a recent trip to USS Harry S. Truman.

"It's our first and only night on board the USS Harry S. Truman, one of the most prestigious ships in the American navy, and I'm cursing a nearby door that won't stop slamming.

"Groggily descending from the bunk bed, I realise that the adjacent corridor is as busy with sailors as during daytime."